IMO, using PBB or equivalent makes it mandatory to split the calipers and replace the seal between the halves. Which I guess is what you wanted to do anyway
Point being that the solvent/oil may attack and soften the seal, allowing it to leak later on. Plus anything that you don't get thoroughly cleaned out may do the same to the new seals.
One way around this is to use the car's brake system to force the pistons out. It will generate pressures much higher than your shop air. One piston will come out first, of course, so clean it up, put it back in, and use a big C-clamp to hold it in place while you eject the other one.