Of course the food of the moment has nothing to do with appendix rupture...
I had eaten Mexican food the day mine burst.
I think I'll go have some Korean BBQ this weekend.
However, for that first tweet pic to have anything to do with an appendix, the pic must be a mirror selfie. It does seem like one. If it's a pic of Frank in the mirror, then the lowest apparent incision would be on the proper side of his body, in about the right place for the appendix. It's puzzling that there were three apparent incisions; I only had one incision, about 1.5" long, from my appendix removal.
There may, or may not have been an appendix removed; my guess is it may have been removed, but as a secondary procedure, oh-by-the-way-while-we're-in-there, we'll take the appendix.
Knowing Pete and the team's philosophy on injury disclosure and avoiding giving any potentially useful information to opponents,, Frank was probably advised not to share specifics and coached to just say his appendix was removed. That part could indeed be truthful, "Deceive with the truth", a partial truth.