Being in a relationship isn't mandatory at any age op.
Parenthood isn't either.
If someone does want to be a parent then there are pros and cons to all ages.
I was married at 22 and ttc at 24 but it wasn't successful for another 4 years when I had dd.
Everyone's circumstances are different.
I knew there was something wrong with me gynaecologically but didn't get a diagnosis until after my 2nd mc.
If I'd ignored the symptoms totally (as my GPs did!) and waited until my 30's to ttc then it's highly likely I'd have never been a mother. That would have broken me.
Within my close circle there is everything from teen mums to those who had their 1st in their 40's for a variety of reasons. Some personal circumstances, some medical reasons - everyone's situation is different
Your son seems to have a good head on his shoulders imo. He's getting himself a secure job in a time of EXTREME financial and employment insecurity and when in the next few years things are likely to get worse!
It's a career with great opportunities not only for training, education and advancement (not just within his work area but anything he's interested in) but also for travel and the opportunity to get involved in charity, sports and all sorts!
Support him and be proud of him.
Most of one side of my family is military and if I could have I'd have joined up myself (medically excluded unfortunately) my ex was army too.
I don't miss the ex but boy I do miss military life!
It's a great community too.
It sounds like your sons friends aren't becoming fathers particularly by choice and that the pregnancies were unplanned and the couples aren't in great positions financially which is gonna be tough for them.
I'd be using their situations to drum into him about contraception to be honest!
In reality with all that considered statistically the chances are that not only will those relationships not last, by the time the children are 5 the fathers will likely have little to do with them sadly.
Your son sounds very clear minded and sensible. That's a good thing.