Obviously the solution is to play one of the millions of fine programs available on the PS Vita which actually handles suspend states exactly how they should be done.
I do have a 3DS (you talked me into Xenoblade Chronicles a long time back and I finally caved on a console to play it and it’s fantastic) and haven’t had any problems with the 3DS power switch, but in those scenarios I would vote for taping something over it so you can’t press it and be satisfied knowing that you can solve a problem Nintendo couldn’t.