It is against the law now, you have to pass a physical agility test though. That might include taking a ladder off of the side of an engine, difficult if you are short.
I think it's more of a combo thing with height and weight. If you're 5' tall, but weight 200lbs then you can't get hired. There's certain weight categories for each height. However, they are fairly large ranges. If you were really 5' tall and 200lbs you wouldn't pass the CPAT anyway.
I don't know what the exact chart looked like, but what I meant was numbers that were obviously not going to make sense for this job. It's more of a making sure you're at a healthy weight for your height which you obviously are.