This sounds wholly inaccurate. It is perfectly legal to buy or sell bitcoins using a bank account. Coinbase does tends of thousands of transactions every day.
Can you post the letter from the bank?
Must be more involved here.
He was moving thousands of dollars through is personal accounts to do arbitrage across exchanges. You should at least talk to your branch manager before starting this kind of activity.
Really. Because using a bank as a bank is a bad thing. But maybe he was using too many free wire transfers..... wait.... wire transfers are not free....
Ok. I get it. They were making too much money on him and wanted to stop.
I could imagine if he was constantly moving money around for free, but not for fees.
This is the way it works (in the US). If he were coming in and making a lot of cash deposits, which are not his usual activity, the teller could file a SAR (suspicious activity report). Even if it wasn't cash, if it was a negotiable instrument like a wire or money order, same thing. The SAR then goes to the bank's BSA/AML compliance department where they determine whether or not to file the SAR. It doesn't need to be a teller, it could really be anyone, bank manager, compliance themselves, or someone in the bank's BSA division. This doesn't mean he's doing anything wrong, just that the activity to them looks suspicious and needs to be examined further. If these steps are not taken, the bank can be fined.
In this case, what's likely happened is they did a risk/reward determination. Is this one person's business worth possibly getting into trouble for. They determined it wasn't and said, "we no longer want your business, here's your money back." They might have very conservative AML laws compared to other banks, who knows. If they had frozen his funds that would be a whole different matter because then they're saying something illegal has occurred but that isn't the case. They just did a CYA move and said go find somebody else.
It's not about making money, it's about operating under crazy regulation that will likely only get worse as time goes on.