CBS owns the license so CBS gets to say what trek is and isn't just like Disney can now say what Star wars is and what it isn't. That's just business.
No it isn't. That isn't how REALITY works.
CBS DOES NOT MAKE STAR TREK. CBS DOES NOT WRITE STAR TREK. They're basically just bankers. All they do is provide funding and enforce the license. That's it. The people who decide canon are the WRITERS OF THE SHOW. These are the people actually making the show. They're the ones that actually craft the story, characters, setting. Do you consider Allen & Unwin the decider of canon for Middle Earth or JRR's Tolkien? If Allen & Unwin, oh boy, Shadow of Mordor is canon, War in the North is Canon, Lord of the Rings Online is canon.
People with the massive cognitive dissonance to not accept that TAS has been heavily retconned out of existence. Because elements of TAS make it into other Star Trek shows, doesn't make TAS canon. They were just testing out ideas that didn't make it into TOS and took the ideas from TAS that they liked and dropped the 95% that didn't.
TNG takes elements of TAS and presents them as new, this is because, The writers do not consider TAS canon.
So if the writers decide what is canon, does that mean that the Discovery writers can decide that actually TOS isn't canon because they want to blow up the Enterprise in the first episode of Discovery season 2? Or could they blow up the enterprise only for her to be rebuilt as an excelsior class ship and redo TOS? Would that become canon?
It would make them shitty hack writers but it would be canon. It would completely BREAK canon but it would still be canon.
Considering how inconsistent Roddenberry was, and the fact that Berman and braga ran the franchise into the ground, i would not trust them if they told me rain was wet.
Yeah trust the hacks suits at CBS who have constantly tried to turn Trek into Star Wars and constantly forced in the worst elements of Trek over the actual creator, show runners and writers of Star Trek. Great choice.

Btw, Leslie Moonves, the guy that says TAS is canon, actually hates Star Trek and Sci-Fi in general.
If Sybok is canon, explain why he is never seen again, never shown in any flash backs, never mentioned by Sarek when talking about his family, never mentioned by Spock when talking about his family, Never mentioned by Amanda when talking about her family.
Sybok isn't canon, he's been retconned out of existence.