Soooo is he still using plumbing fittings? All the 90s I have seen for plumbing are usually pretty short and that would cause a problem for me if I have to go back and unblock pipe.
2" IS 2" provided it is suitable for use with in the walls.This seems to be the biggest offense in all trades.
As far as the 90 d bends. If your dumb enough to suck up the cat...oh well.
Plastic-static is static.
Usually the test is if a regular sized pen can slide around a sweep 90. If piped correctly, these won't go beyond the short 90s on an inlet. But if they do, then the 90s further down the chain should be able to pass it.