When confronted with the apparent contradiction between R. Yochana's let himself be healed by a non-Jew and the problem when R. Abahu should NOT have let himself be healed, why does the gemara require answers like "adam chashuv, rofeh mumcheh or that R. Abahu was different -- why doesn't the gemara simply draw the distinction between a nochri and a min (a distinction it has drawn before and which eventually, tangentially uses when discussing why R. Abahu is different)? On 27b, that distinction is vital and generally applied. Why not draw it on 28a?
Dan, Teaneck, NJ
The Ritva basically asks your question (according to his explanation from a previous Gemara that you may have been referring to). He explains that in our Gemara the Min did not use a Lachash or (alternatively) an obscure treatment that could be ascribed to powers of idolatry. Instead, he gave him a basic well known cure. In such a case it is permitted to be healed by a Min. (See Tosfos 27b, DH "Shani."). This is why this distinction was not able to be made by the Gemara.
All the best,
Yaakov Montrose