I am genuinely curious: Was this at least partially in response to the bots over the weekend spamming "JOIN #LIBERIA ON LIBERIA.CHAT"? Because that probably didn't come from libera staff or even from the libera network, for that matter.
No. It's a response to people trying to leave. The spam bots wave were probably done by the same people doing that for ages (the pedo spam and so on).
You can't answer that question any more than I can. This is a question for Andrew Lee.
I actually can, because (1) freenode mostly had good anti spam software since a while and (2) rasengan and his staff clarified it’s about people moving.