They are not stupid, but they are opportunists who will try to seize any opportunity to seize users' assets. Kucoin will not hand over XMR to the British authorities under any circumstances, despite all these difficulties that they suddenly began to impose without prior notice. Since the assets are stored with them for years, it is easy to target their owner and besiege him with questions for which he cannot find satisfactory solutions.
Op seems to come here just to blame the exchange knowing that he hasn't a lot of options.
This is a very harsh lesson for you and a reminder to the community of the basic principle in crypto "Not your Keys, Not your coins".