Perhaps I'm confused, but this is my assessment of the situation.
The use of the TXT RR is required because of one proprietary system's
partial implementation of the DNS specification, referring to the
RPC-based mechanism.
No, the reason TXT is needed is that only 60% of the deployed
infrastructure is capable of publishing new RRs, and that is
according to a highly optimistic assesment that considers
'support' as 'can be hacked into compliance'.
If you had listened to other people at the face to face rather
than shouting them down you would know that DNSEXT is not an
option here.
Phill