Is that canon? Because David is in college together with Jayce and gang so i thought he would be the same age as them. Macoon and Tom are older while Rask, John and David would be around the same age.
It actually is, which is why Monchi doesn't want to make a route for him (which is completely understandable.)
Monchi's tweets about David:
As to why he's in College despite not being 18, it might just be because he started earlier? Or he was able to skip a grade? Those two reasons come to mind. There isn't actually an explanation for that yet.