if your son just rides around the block, that would be just fine - and a front suspension is a must for obvious social reasons
speaking from experience - if you aim at some longer trips, then depending on where you live, a 3x7/8 bike would make more sense. I was considering a 1x bike for my daughter, but I'm glad I went for a 3x because for a kid even a small 'bump' might turn into a wall, esp on a longer ride. besides IMHO it's good to learn how gears work and how they can improve riding quality and how some roads that look crazy hard (=steep) are easily rideable with a proper gear and tempo.
my daughter's 8 now, but she got her 24" two years ago (she's very tall for her age) and covering larger distances (up to like 30 km at that time) wasn't much of an issue, at least as far as the bike itself is concerned. now she's capable of doing like 50 km+ and still be relatively comfy on her bike, which is just a regular, sort of 'mtb' girls bike. that does speak volumes about how good even those 'cheap' bikes have become, not to mention she's far more into riding I was at her age - heck, I wouldnt go for a 50 km ride until I was like 13 or more.
for "serious" riding I'd opt for stiff fork though, those kid suspensions don't work and do weight significantly more. next year or the year after I'll probably try something more 'roady' for her, although to be honest it's a good idea for a kid to have two bikes - one for playing with friends, second for riding with her daddy