Almost every priest action is a pointless deconvert action. ALWAYS.
Ah...no. First of all, there's that little option labeled "Preach."
Second of all, intent counts. If you're coming straight out and admitting—as you, and several others are—that you are deliberately using the Influence options in order to reduce the number of followers of the religion, that's pretty damning evidence that you're abusing game mechanics.
And every single antecedent has backed up the IR of choosing one's class, regardless of how stupid the contexts were. To decide otherwise now, to overwrite the IRs on such an arbitrary basis, would completely contradict all precedents. A ton of characters became priests for the sole purpose of being immune to expulsion all while abusing of this protection. Their right to remain priests has always been defended and all titan complaints against them has always failed.
You're both welcome and encouraged to remain a priest—once you have founded a new religion to be a priest of. There is no Inalienable Right to be a priest, or follower, of a particular religion.