If everything Walker says is true, then there was some colossal misjudgment on the part of the manager.
On the other hand, we have learned to be suspicious of claims like this where only part of the story is on tape.
Given Walker's apparent connections with radical groups, I think we're right to suspect that
(1) some important details are missing from the story, particularly details about the onset of the incident, and
(2) the whole thing may have been a set-up.
The manager behaved in a bizarre manner. Even if the man was a fraud, it was best to leave it alone, as the $10 loss had already occurred.