"Go back to Digg" - so much about being judgemental.
I don't think that anybody is attacking the guy because of his disability. There are two things that people feel strongly about:
1.) He hasn't got anything else to do or planned. There are so many other things in life - go to the park, go to the library, visit museums and see your friends/family. Build a freaking boat, set your fart on fire, learn a new software or language, get a bike and see your surroundings, get some voluntary work or just clean your place after you redecorated it. Record your own Jackass show, jump off buildings or read an effing book! You know what - read an effing cartoon, if you prefer.
Alternatively, sit on your ass whole day and play on your iPod Touch! The guy doesn't even need a cellphone, letting alone an iPhone with an expensive plan. This is pure gadget-addiction. He's only obsessed with things that are irrelevant in the end - first in line? Cameras on both sides? Come on!
Again, this has nothing to do with his disability.
2.) What has something to do with it is that if you have a disability or a condition, it is also your responsibility to make sure that you are not putting yourself into risk, in this case into the risk of having a seizure. Arguably, sitting outside in hot Texas (even worse, urban Dallas) for a week is a pretty risky move from somebody with a medical condition. If he's having a fit, I'll have no compassion to the man. You have to take responsibility to your actions. Generally speaking, even in the criminal law it is recognised that if you have a condition, that can be a mitigating factor or taken into account as a defence - UNLESS you make the decision of not taking your medication or putting yourself into a situation where your disability/condition is likely to limit your actions.
Some of us know people with disabilities or conditions. I know people with epilepsy and they work in decent jobs. Why? Because they prefer to be in control over their life, rather than living on payouts and feel sorry for themselves. I'd argue that some of us in a medical state that they would not risk a day in the heat, letting alone camping outside a store in a hot and urban environment.