Considering that IRL I'm engaged to a 28 year old, nah, that's not it... I just don't think it works very well with the timelines... Yes, young men join wars all the time at the age of 16... but from all the research I've done, it would appear that he'd been in the war pretty much from the beginning... that'd be 14... ok, still possible, *IF* his homeworld was one of the ones being attacked... but still, sith assassin at 19? ummm... ok... Of course, I guess that would help explain his bizarre thought processes...
1. I hate the jedi - they didn't show up to help us!
2. I love Revan! He helped us defeat the Mandalorians and following him was the right thing to do!
3. All those Jedi at Malachor V, the ones that followed Revan (my hero!) and showed up to help us? They deserved to die!
4. At least the Sith are honest... All Jedi lie!
5. Jedi & Sith are all the same!
6. Then the girl showed up and showed me the force - and I didn't want to be a Sith so I ran away!
Ok... you're right... he could have been 19 when he was recruited to be an elite assassin... why not...