I don't think the argument is "police shouldn't confiscate [stolen] property from somebody they're detaining because of suspicion the individual has committed a crime", it's "police should not take property unrelated to the crime and, in the event the individual is cleared of any wrongdoing, return _all_ property", the latter of which isn't happening.

If it turns out the guy running away from the bank just likes jogging with a bag of money the police should return his money and whatever else _immediately_ after the person is released.