Answer

I once wrestled with a similar question. It is commonly said that there are no disputes about reality. But in fact every dispute is a dispute about reality. The question is what the Holy One, blessed be He, said to Moses at Sinai (or even what He meant). But about that it is said, “It is not in heaven”—meaning, the important question is what we understand, not what the intention was above.
Something similar can be said about disputes over the view of one sage or another. We are not looking for his original intention, but for what his words say to us. That is what matters for Jewish law. Therefore, in traditional learning one hardly ever relies on comparative sources, printed editions and textual versions, or side sources; rather, one examines each text from within, on its own terms. We are not studying Moses ben Maimon; we are studying the Rambam (= the Mishneh Torah). I wrote about this in my article on hermeneutics (you can search for it here on the site).
Beyond that, in many cases when a sage says something, his words can be understood in two ways, and it is not certain that he himself was aware of that. It may be that each of the two sides disputing the interpretation of his words is uncovering something of his original intention.
And one last remark. In most cases it is not all that important what a given sage intended. Clarifying his intention is done only in order to expose another approach within the topic and reveal additional shades that, without analyzing his words, we might not have discovered. In the end, I am supposed to rule according to my own understanding, and the clarification of the different approaches is only a means. So it is not all that important whether we have hit upon the intention of Maimonides or the Rashba. An example of this I brought in my article mentioned above regarding the Maggid Mishneh, who interpreted Maimonides’ words in the laws of hiring in a way that stands against the Talmud. He proposed an innovative approach in interpreting his words, but the Kesef Mishneh there cites Rabbi Abraham, son of Maimonides, as saying that his father said this was a printer’s error. Now the question is what to do with the Maggid Mishneh’s approach. Seemingly, it is founded on a mistake and has no value whatsoever. But I argue that this is not so. If the Maggid Mishneh proposed such an approach and was prepared to stand behind it, then there is another halakhic approach here (even if it is not Maimonides’ own approach). As someone studying the topic and as a halakhic decisor, I would take it into account like any other approach. It does not matter how the approach was discovered so long as it is reasonable and consistent. This is somewhat like the accepted distinction in philosophy of science between the context of discovery and the context of justification.