Yes, I'm still on the fence as to whether the above comment was genuine (in which case I truly can't understand it) or meant as some kind of sarcastic denunciation of this list by showing that you can always find a remote reason to be offended.
It was meant both reasons you give, but come on - it is simple to understand. You know exactly what I mean, and I do find it offensive. But it still is sarcastic at the same time. Things can mean two things at the same time.
But really, what it comes down to, is if someone finds something offensive, you don't use it. 100% it is derogatory word indicating Slavs are equivalent to slaves. If you disagree, you are just being willfully unseeing.