Cejudo's accomplishments are impressive...but there is much room to grow if he wants to truly belong in GOAT discussions (specifically, more defenses).
Parachuting into an undeserved title shot with Volk would be ridiculous. IMHO, it would be more of chasing an accolade than a substantial accomplishment when there are a LOT of contenders at 135 that Cejudo should have defended against, plus he would have beaten ZERO contenders at 145 to actually earn that shot. It would be a win over a legit guy, for sure...and it technically is a title in a third division...but not earning that shot and not defending means that it is not nearly the boon to his legacy that it could be.
Conor and GSP face similar (albeit different from each other) criticisms for their 2nd division titles. The wins are legit...the way they got those shots, and not defending afterwards, means that they should not factor in too strongly into their overall legacies, IMHO. GSP is a GOAT candidate because of his overall WW record, number of defenses, calibre of competition throughout his career, etc...not so much because he beat Bisping in a one-off MW title fight. Conor's in-cage legacy lies primarily at 145 too.