While I can't speak directly to that particular issue of Coinbase seizing user assets, what I can tell you is that I once had my Wells Fargo bank account shut down without warning for conducting trade with Coinbase.

IMHO, there is already a substantial effort to stop bitcoin without having to go through the legal loopholes. Everything from market manipulation to massive power plants being developed exclusively to mine bitcoin and bankrupt pleb miners.

"They" (the banks/Coinbase etc.) are absolutely seizing user funds that are stored on their platform. They will even make up completely bogus charges and put the onus on you as an end user to prove that you aren't doing anything illegal with your own money. I know we all say it but "get your coins off of exchanges as soon as you can."  Custodial bitcoin is the largest contributor to bitcoin price suppression and leading cause of rug pulls.