To quote Rav Shimon Shkop's take on that gemara (Chagigah 15b; translation mine, taken from "Widen Your Tent: Thoughts on Life, Integrity & Joy", ch. 1, available here, pp 71-73):
But to my mind it is worth knowing and
contemplating what our Sages said on
Chagigah 15b. How could Rabbi Meir
receive Torah from the mouth of Acheir
[the former ...