There are two main reasons why you may be worried about violating table manners:

1. Because there are real consequences to doing so.
2. Because you are worried what people who don't know you might think.

For 1: The only real consequences for casual dining situations that I can think of is that, if you are particularly messy, the owner might ask you not to come back. This depends on the owner's personal opinion on what is allowed, and should be clarified with her/him on a case-by-case basis.

For 2: Particularly finicky people around you may not like this. However, that does not prevent you from ignoring table manners, and ultimately depends on how much this bothers you. This cannot be solved the way 1 can (unless you want to talk to everyone around you and explain them what's going on), but neither does it carry consequences the way 1 does. You have to decide for yourself how much you want to be sure you are not getting sideways glances from strangers.

Ultimately, your comfort with table manners is your own decision. May you violate table manners in public due to your disability? Yes. You may violate them even without a disability. There is no law against it. If you are worried about the diner owner, talk to them. They'll appreciate it. If you are worried about strangers, that's a decision only you can make.

Ultimately, your comfort with table manners is your own decision. May you violate table manners in public due to your disability? Yes. You may violate them even without a disability. There is no law against it. 

If you are worried about the diner owner kicking your out, talk to them. They'll appreciate it. 

If you are worried about strangers' sideways glances, I cannot assure you that seeing you eat with your hands will not bother anyone. It will probably bother some. But you know your reasons. If said stranger has nothing better to do than to dwell on the normal-looking person next table who seems to be helping themselves with their hands, let them dwell on it.