My daughter chose cello at that age, and it was good fit. She is very tall, and she's mentioned that her hands are huge for the violin. Now, of course, you would get used to it, but she said that cello was a lot more natural for her given her being tall. She ended up being very successful on it through 8th grade, when she quit the orchestra (band sounded more fun for her).
Does your school offer a "try out the instruments" day? That would give him a chance to hear all of the different instruments, and at least at my daughters, they got to try them all out, and that would be a good way to see which one he likes.
You didn't mention it, but if he does prefer the feel of the violin but does want as "screechy" of a sound, you could try the viola, as it is pitched lower. DD has a very tall guy friend that played viola and he didn't have any problems with it.
