Having seen both parts now, I wonder if there's more to Carl being the Guardian of Forever. It has been suggested that there's a connection between Carl/GoF and the Tkon Guardian. The reveal of who Carl really is convinces me this is almost certainly so and that Carl/GoF is a product of the Tkon Empire.
Makes me wonder if the Tkon used the Guardian or based their Portal technology on it. And then the Tkon Empire got involved in some shady temporal stuff, so the Guardian got rid of them via supernova. When you piss off Carl, he starts supernovas.
Clearly a lot of people after TOS and TAS found out about the Guardian and tried to use it for their own nefarious purposes. There were centuries of history in between the two eras and who knows how many Temporal Cold War soldiers and temporal agents used it to gain access to the past.
Probably read about it in the papers published by Professors Aleek-Om and Grey in the Journal of Temporal Mechanics
And the Federation being the gold standard of "tight security" that they've always been I'm sure they gave up protecting and guarding it at some point and just assumed it would go undiscovered or unused by malevolent agencies.
Yeah, and it's obviously not just a clever statement on his part to muddy the waters and protect his own safety. He was abused as a temporal gateway and relocated himself tens of thousands of light-years across space itself to get away from people who wanted to use him for nefarious purposes. When a GATEWAY moves halfway across the galaxy to get away from your kind you know you've been taking advantage of the thing.
I loved when Carl explained how chill he used to be about people using him to travel through time. He really gave zero fucks
Pardon me whilst I do some FACT TREKing on all this. Mostly because most of the sources fans have access to have repeatedly gotten the particulars wrong about the development of the outlines and script, whereas we (@Harvey and I) have many many if not most of the drafts of it and tracked the changes. The firing squad and environmental suits appear only in the Original Treatment dated March 21, 1966. In the Revised Treatment May 13, 1966 all the firing squad stuff is crossed out and Beckwith flees via the transporter. Thereafter it was always Beckwith (and, finally, McCoy) deliberately beaming down. Kirk reports the planet shouldn't have an atmosphere yet it does, so no environment suits. ^^^This revision process is pretty typical. Ellison wrote his first outline very early on...before there was anything but the two pilots to refer to. He got feedback from the Trek staff on things that didn't fit the planned and developing show format, so out went the firing squad and expensive space suits, etc., and the Revised Treatment reflects this. You are correct that Ellison's original idea was that there were Guardians plural who resided in the titular City on the Edge of forever atop mountains in the distance. But, just to clarify a fundamental difference, the Vortex was less a device for time travel and more a means of accessing and harnessing the flux lines of time and space, which the First Guardian said was because "only here" did all the pulse lines of forever meet. The Guardians plural appear in all the story outlines and the "Writers Draft" script. By the official first draft, the Guardians plural become a single Guardian, "the last of my kind". At no point in any Ellison draft are the humanoid Guardians actually the time vortex, which is what Carl says he is. Even of they had been, it would still not be the original concept, because they were never "statues"; albeit they were basically immobile except for their faces. In summary. Carl is in no way shape or form anything any conception of the Guardian(s) that Ellison ever wrote, regardless of what RMB or any other self-proclaimed authority claims.
In the Q Continuum books, Q said he was a creation of the Q before they ascended into energy beings. In the Yesterdays Son/Time for Yesterday books, several members of the ancient species who built the city around the GoF are said to have travelled through the portal, and a few return very powerful and out of their minds.
He just uses outrage to generate engagement. It's a tired old internet trick that people keep falling for.