THe authorities are hamstrung. They can't fight the left. It's up to the people. Had that group been treated by the people there, as they should have been, it would have been over very quickly. The talk would have gone on without the protesters.
No, the authorities can fight the left, they just choose not to. Bloomberg could have evicted OWS from Zucotti Park after the first couple of days, and the movement would have fizzled. The Oakland Mayor bent over backwards to accommodate Occupy Oakland, until she couldn't ignore their lawlessness any longer. In every major city that the Occupiers have had a prolonged presence, the local government has done everything in its power to aid and abet their lawlessness.