No, it is safe practice. It is part of the brief.
The diver is not being flipped back against their will, they are expecting to go, they are waiting to go.
The buddy checks have been complete, regulators are in each divers mouth and the boat is running onto the shot.
If you don't want to 'go', you lean back into the boat and the bow divers arm just bounces off you.
(If does leave a diver on their own in the water, with the boat having to do a go around to recover the diver.)
You both know that what is going to happen. It is only the diver closest to the bow that puts their arm out. You can always choose to sit in the bow position, but, you do run the risk that the stern diver will land on you!
I was lucky, I only ended up with a tube of superglue in my skull. It could have been a lot worse.