There's a big difference between
The flyers not being able to call him up, which they couldn't because he's unsigned, and outright choosing not to call him up or play him because reasons (see Stankoven last year/this year).
I doubt he's actually pissy over not being able to make about 50k from playing in 10 or so NHL games, especially in the NIL college era. (I'll have to look up his NIL deal at BC, if any) but he probably didn't lose out on much money
He's probably more pissed he didn't get to burn a year off his ELC, or he realized philly is a shitty city.