The 30 post limit came about in a different era, when the list had problems
at a greater scale. I don't see any issues with post frequency recently
that should have received moderator response. You are referring to GerardM,
but the majority of his posts have been to a single thread. I can't speak
to whether that has interfered with that particular thread, but it
certainly hasn't presented any problems to the list as a whole.
By the way, Erik Zachte keeps statistics:
https://stats.wikimedia.org/mail-lists/wikimedia-l.html
Much easier than skimming through a list of posts and trying to count them
up.