Copper anti seize grease as thermal paste?

[lexluthermiester]

No thermal compound or grease, etc "dries out" - it can polymerize and harden

That would be VERY incorrect. Many TIMs use an oil suspension fluid as a base which can and often does evaporate over time, thus the term "dry out".

Silicone oil is used because it's theoretically more resistant to aging.

Not every company uses silicone oil as a suspension fluid.

I'd advise you to look for actual facts and numbers to support your discussions.
This copper anti seize for example has a conductivity of 4.68 W/m-K
https://www.aremco.com/news-item/heat-away-640-thermally-conductive-copper-grease-now-available/

Given that actual testing shows good performance, what would your point be?