At the risk of going around in circles, you need to think about what you mean with "normal circumstances" and "suboptimal". Normal has changed and this could have been said about any other situational move the generation they became useful.The point is that under normal circumstances these moves are not viable, however the fact that you would use otherwise suboptimal moves in order to deal with a mechanic that can not otherwise be easily dealt with shows how overcentralizing dynamax is.
The argument essentially reads "Dynamax is broken because I need to do new things because of it".
I'm not actually invested in using these specific moves and they may still be bad, I just brought them up as an option amongst other viable options.
I'm actually just using Bounce to get at Max Airstream, but I've had Bounce and Phantom Force in particular used effectivly against me - because switching out while Dynamaxed isn't ideal!