Hi,
I can't give you any help as to whether this can/does happen or whether this is a lot of bunk, but I can tell you that this is exactly what they told us about our DS11 when he was evaluated by a developmental optomotrist when he was 8. I do know that, in general, while optomotrists believe in vision therapy, opthalmologists do not.
Your DS sounds exactly like mine. He walked at 7.5 months but never crawled (well, did crawl once at 11 months, so he could physically do it) and talked in two-word sentences at 12 months but never babbled. He is, and has always been, very tactile. He was getting a lot of headaches at school and seemed to be having problems copying from the board to his paper and from a book to paper, so we had him evaluated by a developmental optomotrist. They told us the exact same thing they told you. We did do vision therapy for a year, and their tests showed marked improvement, but IRL I'm not so sure how much it helped. He does say he no longer gets double-vision or the words moving while he reads and he doesn't get those types of headaches anymore. But, he still has big problems reading outloud (not silently or comprehending) so we may have bigger issues.
A lot of my DS's vision therapy involved coordination activities crossing his midline. And, I do have to admit that my son who walked so early and kicked, threw, and caught balls at 12 months is rather uncoordinated and lacks balance and is generally not very athletic. So, I just don't know.
Sorry I don't have anything helpful, but just wanted you to know you're not alone.
P.S. I do know that crawling is not considered a developmental milestone, like sitting up and walking is. Pediatricians are not concerned when kids do not crawl, especially if they use other means to get around. Heck, I never crawled and I turned out just fine!
