I have no doubts that the character identified by the police is an associate of the bikers. That's the sort of thing I trust the police to know. What remains an accusation is that this is the same person who appears in the videos smashing windows and promoting "Free s**t". We don't have the evidence, so we have to guess about whether the police really do have evidence. But I think your earlier statement that there was no significant evidence presumes knowledge about the evidence that you don't actually have.
In other words, whether the anonymous tip is all they have to go on is not public knowledge. I suspect that they have some form of corroboration. If not, I would say they probably screwed up. At this point we out in public-land don't really know.