The DOJ is not closing accounts. Presenting that way is misleading and wrong.
Here's the Wikipedia for the DOJ Operation:
http://en.wikipedia.org/wiki/Operation_Choke_Point
They're investigating banks and related services, and specifically the transactions they conduct with types of businesses that have a history of being used for money laundering and/or fraud.
The bank was in no way obliged to close the account. They
chose to close the account, because they don't want to deal with the government investigation.
It doesn't have anything to do with pressuring companies the President "doesn't like"; dating services, coin dealers, money transfer networks, these are all on the list too.
It may not be the best way to go about this, but it isn't what the article claims. That's a business owner who didn't understand what the bank told him, projecting his political beliefs into the situation, because clearly Obama has to be to blame for the bank not wanting his business.