Every bank has its own rules when it comes to cryptocurrencies, some explicitly forbid it, others keep it in a gray zone, for others only profit is important and they do not create problems for their clients.
As for HSBC, I’m honestly surprised that they’ve become so careful about where clients ’money comes from and even more where it goes - since a few years ago they laundered money for drug cartels and received loads of money in trucks. The bank that was established
as a source of funding for the giant trade of opium into the Chinese markets in the nineteeth century, should no longer even exist if there was law and justice.
My advice is to change the bank, but first send an official letter and find out what is allowed and what is not.
Man, what they don't want is to be challenged. As they are dedicated to money laundering, they are terrified of cryptocurrencies, because they can take clients away from them, and that is why they try to prevent them from being used, in vain, of course.