I won't go so far as to say HSBC colluded with the USA.
The trading currency of multinational banks is the US Dollar, so when Uncle Sam and his men in black come knocking on your door and demand answers to a few questions, it would take a very hard nose branch manager to say, "you **ss off and get out of my bank" to them.
Having said that, I would guess a Chinese bank would have done more to protect their Chinese client.
Let the Huawei Weng episode be a lesson learn by mainland business companies.
Despite HSBC's name, 'the Hong Kong and Shanghai Bank", it is a very pedigree British Bank.
Indeed it would be very dangerous for the mainland China authority to treat the HSBC as a "Hong Kong" bank.
The US Government must have raked in hundreds of billiions over the past three decades from multinational companies around the world for breaking US issued sanctions.
Sanction have become a business strategy for incumbent US government.
Trading with the US is fast becoming a liability for many multinationals.
Europeans are getting this message loud and clear. They are retreating from the US fast and fury.