Unfortunately you haven't established that at all.   I count maybe 3 or 4 people that think there's a specific list of criteria.   A list which would invalidate Armageddon, BTW.   It would seem that the list of specific criteria are nonsense as Armeggedon is certainly an RPI mud.   I don't see any disagreement with that here.  

I also cannot find history of the term in regards to the criteria you posted.  No not even in the conversations you posted from '97, which are laced with "IMHO".   Robbert implied that maybe exploring the history of the term wasn't a good idea.   I can understand why.   There isn't any.   Well actually there is a history of people apparently using the term quite loosely from 98 onwards.   (i.e. Nimud, SwordQuest).  

The term is obviously not pure, and never has been pure.  It's kind of late in the game to start enforcing some sort of specific criteria and/or ownership of some acronym.  If you've gotta say, well "RPI is Harshlands" then you might as well not even bother clarifying it as nobody is ever going to be remotely confused by the term RPI.

I've noted a few muds on TMC put RPI in the codebase portion of their listing.  What's up with that?
Will some committee be approaching MystariaMush to explain that they can't call their game an RPI?

Where is the list of criteria?
Who developed the list?
Who maintains it?