Question

Hello Rabbi,
Regarding someone who delays relieving himself, the halakhic decisors ruled that this involves a prohibition, but I noticed that many Amoraim and Tannaim did not treat this as a prohibition. For example:
Babylonian Talmud, tractate Yevamot 64b
For Rabbi Abba bar Zavda became sterile from Rav Huna’s lecture. Rav Giddel became sterile from Rav Huna’s lecture. Rabbi Chelbo became sterile from Rav Huna’s lecture. Rav Sheshet became sterile from Rav Huna’s lecture. Rav Acha bar Yaakov was seized by saskinta, they hung him on a cedar in the study hall, and something green like a palm leaf came out of him. Rav Acha bar Yaakov said: I was one of sixty elders, and all of them became sterile from Rav Huna’s lecture except for me, because I fulfilled for myself the verse: “Wisdom preserves the life of him who has it.”
It seems from here that Rabbi Abba bar Zavda, Rav Giddel, Rabbi Chelbo, Rav Sheshet, and another sixty elders all delayed their bodily needs, and as a result became sterile. Seemingly, the Talmud should have asked how all these people violated the prohibition of “do not make yourselves abominable,” but it does not ask that.
Babylonian Talmud, tractate Gittin 70a
Rabbi Chiyya taught: One who wants not to suffer intestinal illness should regularly eat foods dipped [in liquid] in summer and winter, after a meal from which you enjoyed yourself withdraw your hand from it, and do not delay relieving yourself when you need to.
From here too it seems that avoiding delay in relieving oneself is only a good health practice, and perhaps there is a prohibition because of harm to one’s health, but not a prohibition of “do not make yourselves abominable.”
This also seems implied by Bekhorot:
Babylonian Talmud, tractate Bekhorot 44b
The Gemara says: Rabbi Abba, son of Rabbi Chiyya bar Abba, said: One may urinate in public, but one may not drink water in public. And it was also taught likewise: One may urinate in public, but one may not drink water in public. And there was an incident involving a certain person who wished to urinate but did not urinate, and his belly became swollen. Shmuel needed to urinate on the Sabbath of the festival pilgrimage; they drew a curtain around him with a cloak. He came before his father, who said to him: I would give you four hundred zuz and go do it again—what was possible for you, while for him it was impossible, should he endanger himself? Mar bar Rav Ashi needed to urinate by a camel trough. They said to him: Your mother-in-law is coming! He said to them: Let her come into my ear. But let this be prohibited because of an evil eye? Where it is merely trickling, it is different. The Sages taught: A person has two openings, one for urine and one for semen, and between them there is only something like the thickness of a garlic peel. When a person needs [to relieve himself], if one opening enters the other, he becomes sterile. Reish Lakish said: What is the meaning of that which is written, “There shall not be among you male or female barren, or among your cattle”? When will there not be among you a barren male? When you are like your cattle. Rabbi Yehoshua ben Levi said: “There shall not be among you a barren male” — among the students; “or female barren” — that your prayer should not be barren before the Omnipresent. When is that? When you make yourself like an animal. Rav Pappa said: A person should not urinate on an earthenware vessel, nor on hard ground, for Rav said: These splash-backs of Babylonia return the water to Ein Eitam. Abaye said: A woman should not stand directly facing a child, but from the side there is no problem. It was taught: Rabban Shimon ben Gamliel says: Returning spray brings a person to dropsy; a returning stream brings a person to jaundice. Rabbah bar Rav Huna said that Rav Katina said that Reish Lakish said: Much blood leads to severe boils; much semen leads to severe tzara’at; much feces leads to severe dropsy; much urine leads to severe jaundice.
Babylonian Talmud, tractate Makkot 16b
Rav Aḥai said: One who delays his bodily needs violates “do not make yourselves abominable.”
It seems to me that the idea behind this statement of Rav Aḥai is that delaying one’s bodily needs is an act that harms a person medically and can even cause sterility, and therefore he prohibits it because of the prohibition of “do not make yourselves abominable” (this view was apparently very common among the Sages in light of the sources above). Another possibility is that this is an intrinsically disgusting act (like eating things mixed with vomit or feces), but it seems to me that most people do not regard the act of holding oneself in as a disgusting act comparable to someone eating something mixed with vomit (for example, when a person watches someone else eating feces, you can see the feeling of disgust on the observer’s face, but if a person watches someone else holding in his bodily needs, you don’t see an expression of disgust on his face). Therefore it seems more reasonable to say that what led to the ruling that delaying bodily needs falls under “do not make yourselves abominable” is the health danger involved, not a feeling of disgust.
In light of the findings of modern medicine, it is known that delaying bodily needs does not cause any special health problems and also does not cause sterility (unless we are talking about someone who delays in a very extreme way, in which case he may develop a chronic difficulty fully emptying the bladder; this happens to truck drivers who hold it in for long periods on the road, but most people do not reach that point even without a prohibition of “do not make yourselves abominable”). Would it be correct to say that in light of today’s scientific knowledge, there is no prohibition of “do not make yourselves abominable” in delaying one’s bodily needs (since Rav Aḥai’s statement was based on a factual mistake, such a statement has no authority for later generations)? 
With blessings,