DS has asperger's and is hypermobile and yep there does seem to be some relationship between ASDs and hypermobility - but they don't always go together
I'm hypermobile, didn't realise it till I had DS right enough because it's never caused me any massive issues, my handwriting's not fantastic and never was, I can't ride a bike (but that's partly circumstances) and I do things like go over my ankles a lot, but that's about it, lol. I'm fairly sure I don't have an ASD, rofl.
DS can't write legibly at all, his fine motor control is terrible, but he can ride a bike and isn't clumsy in a falling over way, my friend's wee one with AS and hypermobility has fantastic fine motor control, but can't ride a bike and can fall off the floor while she's sitting down.
DD is absolutely NT but I had her checked by the consultant as a toddler because her feet were turning out, she's officially 'on the bendy side of normal' lol, it doesn't cause her any hassle at all.
I also have a friend who's hypermobile (with no other conditions) who as she's got older it has caused a bit of joint pain and has a more than usual tendency for dislocating shoulders or elbows when she has an accident - but it's never affected her mobility in any way.
So, all anecdotal obviously, but I'm fairly sure it doesn't mean anything else has to be present - and it could affect him in various ways, so it's entirely possible that it won't cause him any major issues