Dont be dumb man. Responsibility is one thing. I get that. But saying a person shouldnt have sex or have a kid just because they were dealt a bad hand and have a disability is downright stupid.
I get your point, but they can have as much sex as they want to, there's a thing called birth control ;-)
They also, of corse, have the right to have children.
But on the other hand if you're in that situation, you might think twice about that because of the responsibility you have for your future child(ren): You have to provide for them and obviously at that point your just not in a situation where that's a given. And even if you have no problem relying on the government or other people in general to help you (and your future children) out, is that really the foundation you want to build your life and your kid's life on? I mean there is no guarantee that one or two years from now these people or your government will (be able) to help you out and imo that's at least something you should consider before having children.
Of corse anybody can get into such a situation where (s)he loses his job, maybe gets seriously injured/sick and pretty much loses everything and needs to rely on others to survive/get back on his feet, but if that situation is actually your current state of life or a very likely scenario you could find yourself in, you shouldn't deliberately put a child into such a bad situation with yourself.
So if I was in such a situation, I think I shouldn't have a kid...but then again I never felt the urge to have kids anyways, so maybe that influences my point of view...either way everybody has to make his own decisions.