I don't see limiting newbies' ability to post in the lending board as having a big affect on the forum.
It's not big, but it's also another step on a slippery slope. Every time I see someone argue for more restrictions, I appreciate theymos' hands-off approach more.
Newbies already have a similar limitation, they cannot post on the Serious Discussion boards. I am all for this.
Having a bunch of newbies who keep asking for a loan without collateral or anything to end up red tagged seems to me a worse effect for them than simply limiting them from posting there until they are at least a jr member.