You could, but the harm is already done, isn't it?

The harm is ongoing if he's still unable to access his money. Banks will often move quickly once regulators start getting involved.

How long do they take in processing the complaint? What if (s)he is traveling and thus put in a difficult situation?

According to the thread, they've already returned from their travels and visited several different local bank branches. Not sure how long the CFPB or OCC takes to respond, but they do take complaints seriously and they can cause serious problems for banks.