good idea but for example maybe its possible to add some allowed date registration range, i. e. allow posting for newbies that are registered no less than week/month ago.
Yes, too have a good point but still it would make the process more complex and also some multi account spams have older accounts which they can use for spamming. So I think just making it unbumpable ( selfmade word

) for any type of newbie will be the perfect remedie for this.
well, some light was shed on the problem. but i can't get just one thing why local ru mods didn't ban this very active flooder (i. e. all his accounts)? there is plenty of evidence but a complete lack of action.