The gemara had solved the problem of a contradiction in the words of R. Yohanan and yet does not rely on the answer ( terutz) for pesak.
And yet in Gittin 27 a we find a contradiction in Rabbah and answer with kan bemakom shehshyorot metzuyot kan bemakom shein etc and we rely on that difference halakha lema'aseh (see Rambam and Tur)??
The difference is that there is clearly a very strong logic in our Gemara to say that these two Amoraim are arguing in Rebbi Yochanan. This is why the Gemara here interrupts the answer by saying "and we should rely on this answer?" It does not so so in Gitin. Additionally, the Gemara explicitly quotes Rava as endorsing that it is not at all certain that this is not an argument. In Gitin the Gemara not only knows the answer is correct because it explains Rabah, but also because it explains a contradiction between a Mishna and Beraisa. It is therefore a much more solid answer.
All the best,