I don’t think this system will work. If we are to implement this then automatically deleted posts with associated merits will be removed.  This will affect innocent users, for example if I get merits in a thread and after a while the OP decides to delete the topic, is it fair that I lose those merits?

I know some will say, "Sometimes a deserving post with merits gets removed because of a removal of a thread/topc."

~
~

Now, talking about exceptions. I know that when a thread or topic gets removed, users who might have posted in that thread and received merits will also have their posts removed as a result of the thread getting removed, in such a case, the merits should stay. But if OP had received merits and it gets deleted from a moderator for breaking a rule, he should lose the merits.