SCUBA, LASER, JPEG, ROM, etc. all break the “pronounced as the nested word” argument.
I’m down for people to pronounce it however they please (assuming it’s recognizable as gif), but the post-hoc rationalizations trying to prove their side as the one true pronunciation are silly. The only rationalization that makes any sense to me is the “creator pronounces it as jif”, but language doesn’t work that way so even that doesn’t matter as far as “one true pronunciation” goes.