I'd be perfectly fine with him staying in AAA all year and then delivering the Phillies a ROTY and accompanying incentives next year.
Arguably even if Nola goes on the IL or somehow loses his spot, Walker is who steps in.
But the narrative had always been that Painter was ready to be the #5 starter with a higher ceiling in '23, and would thus pick up right where he left off two years later.
I don't think they want to make him a reliever, but if he's looking good in August and only has 40 innings to spare, you can use him that way. And in the playoffs he and several SPs will be relievers.