Most of the infinite loop shenanigans don't actually work since bonuses from the same source don't stack unless they explicitly say otherwise.
This one would as-written, though, because it says 'gains +4 Con as if through level gain', and level gain bonuses to stats are specifically given to stack with themselves and other bonuses. And knowing Frank+K, I wouldn't be entirely against the possibility that this sort of thing was intentional.
Most infinite loop shenanigans work because they find workarounds for the 'same source doesn't stack', either by using something that gives an exception or not trying to stack 'bonuses', which are explicitly defined in the rules. But that's why they're shenanigans, and the subgroup of people both smart enough to figure them out and unscrupulous enough to try and use them are vanishingly small.
Things like that were always more in the realm of "Theoretically you could do this" anyway. I don't think anyone who has played the game (or any PnP RPG) would believe bringing something like that into play would be a good idea.
Basically this. It's why stuff like Pun-Pun (the original version) was both legal and firmly flagged as Theoretical Optimization, the intent was never to create something that would see the light of actual play.