Decentralized stable coins like DAI is another choice if you still want to hold the funds in a stable coin instead of fiat but it has low trading volume unlike USDT so it doesn't really serve the purpose of liquidation when it's needed so the best choice is keep the stash in bitcoin if it's meant to be long term.

But not someone can freeze funds on any address it's only possible if government issued the approval of doing that because the funds were involved in a scam or hack.