He has the democratic right to air his political views without intimidation, threats or assault. As do the YES camp, obviously. There's absolutely no excuse for this kind of behaviour.
The guy in Iainmac's picture is not the perpetrator, it's that ugly beaky bigoted yob above. Only a matter of time before he gets his collar felt, fortunately, and he'll be extremely sorry when he is identified - he'll be a pariah both for the NO supporters who he is trying to intimidate and the YES supporters whose name he has besmirched.
The attempts on this thread, and elsewhere, to cry some sort of conspiracy are utterly pathetic.