You love to have your whipping boys. The guy's been in the major leagues for a a few months. Kingery hasn't done much more. Franco still hasn't proven he's anything other than a replacement level player overall (and just got benched two days in a row for Pedro Florimon and Mitch Walding). Aaron Altherr was hitting .198 last I checked. They've all got a lot left to prove, and in their own way are all expendable, in the event of a trade or free agent move. But it certainly doesn't help the Phillies to give up on any of them prematurely, regardless of whether they ultimately play here or elsewhere. They could have given up on Hernandez too.
Plus, until it all shakes out a young, controllable SS who doesn't hit a lick but still has the upside of, let's say, Freddy Galvis, is a perfectly fine thing to have on your bench. Especially since Kapler is not going to stop doing the multi-position thing.
Don't get me wrong, I'd consider trading him for Machado, or trading him if you get Machado, but making Kingery the Phillies SS of the future - or even the next month - is not the move.