I think the difference is that if you say those things at a Republican rally you know what you're getting into. The thing that I think is really off-putting about a certain brand of political correctness (which include the post by puranjay) is when well-meaning people with no ill-intention are chastised as ignorant at best, bigots at worst. For example the post by puranjay, what exactly does he want? It's not reasonable to expect everyone to know everything about every other culture. It's just going to make people resentful.