No. What you do is play Seeler until Fletcher, in consultation with the LHV HC, decide that a prospect is ready for full-time duty. That's how it should work anywhere.
Last season York was 20 and Zamula 21, both had missed PT the last two years, so neither should have been rushed. They might have been too conservative with York, but we're talking weeks or maybe a month, he wasn't ready to start the season. Zamula was injured to start the season, then got ill and lost 10 lbs mid-season, and was up and down at times in LHV, so he basically took himself out of the picture for a while.
Newhook wasn't even playing in the POs, despite 4 "scrubs" ahead of him, it took a Burakovsky meltdown for him to get into the lineup. This was despite playing 71 games in the regular season at 21 years old. Flyers aren't the only team where veterans "block" prospects.