I quite don't believe in his claims.
A reputable bank will not close accounts of it's clients unless violating some legal aspects of their financial terms also closing account means only freeze until further investigation. If does happen, then a client can go directly to the higher state of the law to sued a case. But prior to that, there will be exchange arguments from both parties since reputable bank didn't want to give dirt to their names just because of one person even it has a possession of millions amount of money. It''s against the law that a bank will close account "with no other reason".
If OP is really mad then he can give a shameful comments to that bank throughout social medias. Named that bank and spread the word of yours.
Give your reputation in this forum, I can tell it's a subsidiary of Bank of America. I had unpleasant experience with them. Lesson learned, you should always keep most of your assets under direct control, and keep no more than $1000 in banks.
Well, that bank not quite familiar to me as I do not reside in the US nor to a place where such bank have subsidiaries. I believe it's almost the same banking principle they are using as banks has a central bank that monitored them.
With relation to the problem, not in my life I have experience my account has been close, God forbid but my experience as a banker, we only close or freeze accounts when there's an order by the court to do so.
In a day to day operation of the bank as well, we do receive memorandum from AMLC for suspicious person and we double check it with our system and report directly to them in an encrypted report file.