Been awhile since I posted here. Sorry, I think your friend will find they will not take her. Why? Not because she can't use her hand- you said that she can, but the bare fact is, with so many applying why would they take one who has this problem when they can choose others who don't?
Of course, my personal feeling is that I hope her personality & skills shows through, because that is the more important thing; but having lived here now I can tell you that things are not always fair as if we would want them to be.
Perhaps she will get the perfect recruiter on the day who is wiling to give her a chance, but then, it is also up to GCAA to approve the medical checks.
Try Google GCAA and see if you can find anything about it. If it doesn't mention, then go for it