I'm curious - if this fix goes in, and you upgrade fanaticus, will federation choke if the back-end of the client instance isn't upgraded? (~~It looks like a fix is checked in, but hasn't been released.~~ In theory you could run a fixed branch / patch your instance, but I don't know what that would break)
Correct. It sounds like the database isn't constrained, but I don't know if it does the size check on federation. I'd think it would have to, or it could be a security/ddos exploit.