There was a gentleman who came to learn at the school I train at. He could see some outlines of figures but, was legally blind. For a white belt he did sufficiently good and was capable of executing techniques. He trained for a couple of months then dropped off and did not come back. Nobody mistreated him and we were all impressed by his determination and attitude. I am pretty sure he mentioned that he study another martial art prior.
Looking back at the posts I think that the distinction between what a "blind" person can do, and what the best martial art for a "blind" person is - is not being made.
I am absolutely confident that a legally blind person can be accommodated into a functioning aikido dojo and get something out of it and at the same time not disrupt the training. As with anyone I am absolutely sure that there is the same probability that truly exceptional individuals will emerge.
Leaving after two months does not show much determination - perhaps though he found that aikido did not fit all that well.