Oh for goodness sakes.. Can we all just get over ourselves here.
Personally, I thought it was amusing.. A bit of lighthearted humour, that doesn't really hurt anyone.. Man if we can't laugh at ourselves then we spend the WHOLE time all wound up.
I laugh at my own ridiculousness DAILY! Does it mean that I fly totally off the handle every time someone takes the mickey? NO WAY!
It wasn't directed at anyone specific so I can't see how it's a slurr.. Now if he'd said.. "Hey you, blind person, you're rubbish because you can't see" I could see how someone would take offence..
But seriously guys.. You really have FAR too much time on your hands, and too little to think about if you find that offensive.. I'm sorry, but it's true.