1) I don’t think the fear of anyone creating a D&D killer based on the OGL stuff was ever rational
You, in 2024, do not believe it seems plausible (and I honestly somewhat agree with you). That doesn't necessarily mean a rational person in Cocks position in the past half decade could not rationally believe it is possible (and frankly, someone in that position has contacts in that world).
It is worth noting that after the OGL thing, by a brief amount (so it had been in the work for a while) Mark Zuckerberg did premiere an AI virtual reality DM using Snoop Dog's voice...so this might be something people have been interested ding to do, even if you and don6t't think they would have succeeded: the attempt may have turned out very bad for WotC and the D&D community.
So, since reasonable minds can differ, I can grant thst the fears Brink voiced can have been very real
in Chris Cocks mind and almost more importantly
in Mark Zuckerberg's mind.
2) the CC in no way prevents it or is a stronger separation of D&D from that other product than the OGL would have been
For you, me, and "in the know" hobbyists? No.
for the general public, seeing a licensed "anti-woke game the way Gary Gygax would have wanted it, using the current rules of the world's first roleplaying game"?
Again, rational minds can filter, and I can accept that someone was scared of this. And I do think that in this case, the CC being generally understood public domain means WotC can
effectively distance themselves from bad actors like a LaNassa with more money (sadly possible). I do not think that WotC's legal troubles with Nu-TSR, comical as they are, had zero influence on these events: imagine if the richest man on Earth tried to pull the same stunts.
So in the end they caused all of this over nothing and gained nothing from it.
Well, I do think they gained the ability to distance themselves from bad actors, so not nothing: and I believe that ia why they went with CC, aside from being a final resolution that cannot be changed.