On the one hand I generally think there's no harm in trying... why not?
But just a note of caution: my kids were also interested in the guitar at one point and I bought them both child sized guitars for Christmas (I wouldn't let them near my Takamine

) It was just too soon for their hands and they abandoned it quickly. I can't remember their ages at the time but I'll guess around 5-7?
They both love music - they play piano - but now (at 11 & 12) they have no interest in returning to guitar because they see it as "too difficult" and "too uncomfortable." I think this is because they tried it too young.
Worth noting, however, is that both my kids have sensory issues, so that may be a factor. Still... for guitar it may be a better option to wait it out so that a child's first exposure is not a physically painful one.
It seems like I'm in the minority here. I don't think it'd hurt to give it a try as long as his instrument is properly sized.
When I looked into it, the smallest fractional guitar I could find was 1/4 and it was sized for 4-6 year olds. Does his school have smaller guitars for younger students?