I think a little wiggle room is required on the accepted use of $_POST. As long as the $_POST variable is ran through Tools::safePostVars() before it's used I really don't see the issue with it.
I guess the main issue is the Addons team just don't have the time to police every modules code, so they just outright refuse all use of $_POST to be safe.
A quick solution would be just to make Tools::safePostVars() return $_POST after it was done with it.