I wouldn’t think of it as that. The funds wouldn’t leave the mint’s control.

Course funds in the maker offer, while waiting for a taker wouldn’t be available for immediate withdrawal.

So a mint would likely have to keep a reserve of UTXOs not offered for coin joins.

I think withdrawals could be handled by withdrawing non offered funds first, and then rescinding the offered funds if needed.

Keep the questions coming! We were just spit balling over lunch.