They obviously don't like Guelph for his development.
I'm sure they'd like Guelph to trade him to London or Windsor or another top OHL program, but they can't force that.
So keeping him in Philly for a month allows them to give him a lot of hands on coaching before sending him down.
He'd play a couple months, then the WJC-20, then a couple more months, assuming Guelph misses the POs, then either the Flyers or Phantoms - Guelph's last game is March 21.
I think they'll give him his 9 games or so, there have been flashes, and if Grebenkin and Jett show some chemistry they might keep him up, figuring limited minutes this year would prepare him for a top 9 role next season. But if Grebenkin moves up to play with Zegras and Michkov, I think they send Jett down b/c Dvorak - Jett - Hathaway is not ideal for developing his offensive game.
Either way, I don't think they're as concerned as the fans with his development. They knew he was a season behind his peers when they drafted him, from their perspective, playing NHL, OHL, WJC-20 and AHL (including POs) again will probably be about as much experience (with 20+ games against NHL/AHL players) as he'd get in college.