If you're from Derry, you pretty much have the politics behind it engrained in you. He'll know of the politics behind it.
But I do agree that the refusal to wear it falls pretty hollow when you're being paid by an English club, and living here. And if Argentinian players can bring themselves to wear it, as has been said, then let's be honest you should probably grow up and leave the sectarianism out of it.
The actions of the British Army in Ireland were truly appalling, but they were faced with similar. It was a war, it's in the past. I'm Northern Irish as well, coincidentally, and don't have a "side".