I'd choose adding a new board with certain restrictions over restricting existing boards.
People are looking for some necessary boards like Cybersecurity and Privacy and some others are looking for their Local boards as well. I am not sure if it takes extra time to code or maybe theymos just felt like those are not necessary at this moment. But, I don't think we will have a new board for similar reasons. I mean we have a Lending board, Adding another board for a similar purpose won't be approved.
I've seen similar suggestions before. Why not make use of the self-moderation feature? It could even be maintained by a user bot.
Yes. Lenders can create self-moderated threads so they can delete posts from newbies. But, if someone decides to troll them, it's frustrating to do Tom and Jerry fight. I guess once I've seen BitcoinGirl.Club Deleted Ratimov's post from a self-moderated thread and Ratimov kept posted a few times. BitcoinGirl.Club kept deleting his posts. It continued for several minutes.
Well if you want to open a lending thread you could always make it "self moderated" and delete all the unwanted customers.
I know that's extra work but an option.
Yes. It's a good option. Read above.