Think we probably need to focus on the precise legal justification for the action that was taken against DSS. At the very least it seems questionable, and particularly in the context of the apparent lack of action against significant numbers of Celtic/OF fans chanting rather more offensively tendentious political sentiments. The question of the quality of the stewards that other large clubs bring to Greenhill Road is definitely one that urgently needs raising in this context (it's otherwise a very good idea).
The intention is to clamp down on racist or sectarian abuse at football grounds, which is laudable, and which I'd suggest nobody could reasonably argue with. However, there does seem to be some confusion amongst stewards and supervisors as to what does and does not constitute this sort of abuse. A Spotters' Guide might be the solution, but at the very least I think that a measure of improved training of all ground supervision staff wouldn't go amiss.
Too many people are focusing on the red herring of why would DSS want to shout "Free Palestine" in the first place. People have been screaming all manner of odd things from terraces at Love Street and at Greenhill Road for 140 odd years. Yes, "Free Palestine" is political. But it's not exactly sectarian, nor racist, nor even particularly hateful. As Bluto points out, it's an assertion of a legitimate human rights aspiration, perhaps a little out of context at Greenhill Road, but then when were human rights aspirations ever limited by the specifics of geography?
Given that Sunderland FC have just appointed a fascist sympathiser as their manager, and that their chairman has disgracefully tried to justify this gross offence to the sons and daughters of Sunderland that fought fascism in war to protect their way of life by asserting that politics should be kept out of sport, but the people of Sunderland are showing signs of having none of this nonsense, we need to remember that keeping politics and sport separate is not only impossible, it's not actually very desirable.
I really don't think that there is any imminent danger of Scottish football being infected by Israeli/Palestine sectarianism in the way that Northern Irish sectarianism has blighted the game for generations. Though of course we need to be wary, arresting people for espousing a free Palestine at football matches is just un-necessary.