The Nop team is taking care of the spam during their working hours. The main problem arises when they are out of work. I suggest giving MVPs credentials to unpublish spam and to block spammers.
I think the simplest solution is still the very first one on the thread...
" a button for users to mark the post as spam [x], multiple users marking a post as such would hide it ..."
And, as pointed about by other, there is no need for "once they are a reputable user". "Reputable users" are not going to be marking spam things that are not, or face getting removed themselves, and the "multiple users" needed is the check/balance.