I would not assume that an archetype published outside Ultimate Psionics would be included in a campaign that specified only Ultimate Psionics as allowed DSP material. So you’re basically wrong if you think you can get out of listing every book that way (why not just say all DSP? or invite people to ask about 3pp books, and allow/disallow material on a case-by-case basis?)
I really do not want for tactician to be the only psionic leader ever and every psionic class that wants to do any leading has to be a tactician archetype. That’s awful.
It’s also already not true, the vitalist exists, the psion can certainly do leadership if he wants to, and so on.
Finally, I also disagree that making highlord a tactician archetype would be giving the tactician any “needed love.” That wouldn’t be giving tactician any love, it would be at best giving lip-service to the idea. The highlord-as-a-tactician-archetype would be a tactician in name only if we’re going so far as to rip out almost all of the unique tactician class features, massively downgrade its manifesting ability, and introducing an entire other subsystem to the class.
Well, even just having skimmed the highlord, I completely disagree with your assessment, but it’s too subjective for me to actually try to convince you on that.
I don’t personally like that idea much at all.