That's why I said it had to be x number of different members, where x is greater than 1 (and less than, say, 10), and that the temp-ban could be appealed in meta - if a moderator/admin looks at the offender's post history and sees that they are not, in fact, shitposts/scams/etc. then it would be those who unfairly reported the posts that get the ban.
I still don't think this would work. There are a number of members with large numbers of alt accounts who could still easily abuse this, and mods are busy enough as it is without having a bunch of fake bans to review.
Okay, so you don't like my suggestion but didn't suggest an alternate approach yourself... Forgive me if I don't take your rebuttal too seriously, then.