Police officers don't have carte blanche to issue orders and force people to comply. We're a nation of laws (supposedly). They were asked to move and they understandably wanted to know where they should move. Then they were arrested.
Police officers have the authority to make quick judgement calls in many situations. Obviously we are all human and I could ask why and try to plead my case, but I should also expect that after some time of non-compliancy I may be detained. The felony is called something like "failure to obey a police officer".
And it's in the laws of the nation.