I try to use the word MUST to constrain agents in processes, not to just make declarative statements; i.e. I think it's a misuse of RFC2119 to say things like "2 + 2 MUST be 4" or "every attribute value in an XML document MUST be quoted." Better to just say "2 + 2 is 4" and "every attribute value in an XML document is quoted." MUST should be reserved for cases like "you MUST be 4 feet tall to ride the rollercoaster." i.e. every MUST has an implicit "or else."
Using that design pattern, I might change the declarative "every TR MUST be valid" into a process constraint like:
Whereas we've agreed it's worthwhile to get old TRs to be valid [presuming we do agree to that], the webmaster/comm team may decline any publication request if the staff contact of the request is also the staff contact of any older tech reports that are not valid.
See also: earlier collected wisdom on preparing tech reports; timbl's note on what is a specification; a related thread on www-qa