I did change the text, because sometimes a signature is removed for a reason that isn't covered by the rules. I also added logging of avatar/sig removals, so now admins can tell if something was actually removed by a moderator, and which moderator it was.
I like the idea of preventing fake "removed by mod" signatures, but it would have the same problem as word filters...
"Signäture removed by moderatör"
or they could use something less obvious like Alt+0160.