Question

The Talmud in Shabbat 123 discusses the laws of muktzeh. It relates that in the days of Nehemiah they decreed a prohibition on moving all utensils (Tosafot exclude plates and cups), and over time they permitted them in several stages, until the muktzeh laws of the Tannaim.
 
“Rabbi Elazar said: the rods, the poles, the bolt, and the mortar were all taught before the permission to move utensils was granted. Rods — as we learned: neither arranging the rods nor removing them [in the Temple, they would place rods between the loaves of the showbread to prevent mold] overrides the Sabbath. Poles — as we learned: there were thin, smooth poles there, and he would place it on his shoulder and on his fellow’s shoulder, and hang up and flay. Rabbi Elazar said: if the fourteenth [of Nisan] fell on the Sabbath, he places his hand on his fellow’s shoulder, and his fellow’s hand on his shoulder, and hangs up and flays…. Rabbah said: From where do you know? Perhaps I could say to you that they were always taught after utensils were permitted. What is the reason with the rods? Because of mold; in this short time it will not become moldy. The poles — it is possible to manage in accordance with Rabbi Elazar.”
I do not understand Rabbah’s rejection very well. He is essentially arguing: it may be that the mishnayot about rods/poles were taught after utensils were permitted, except that rods/poles specifically were not permitted, because one can manage without them.
Does it follow from this that even for utensils that were permitted (and here we are speaking of utensils whose primary function is for permitted use), the permission applies only when there is some “need”? And what is the definition of such a need?
The Rashba, Ritva, and Tosafot HaRosh say that in the case of the rods, since the molding until after the Sabbath is negligible, this is considered moving “from sun to shade.” But that answer does not work regarding the poles used for flaying the Passover offering.