If he can’t roll from front to back I don’t think they advice letting them sleep on their front x
I think it's fine, if his head control is good then he can put his head to the side to breathe. Some babies sleep better on their front. I'd leave him to sleep in whatever position he moves himself into
My son has slept on his front since 10 weeks old, only way he will sleep! As long as he’s got good head control, I think it’ll be fine, just my opinion! x
When my son got colic he would never sleep on his back anymore and would only settle on his stomach. When he was younger we’d turn him on his back once asleep but now he is able to roll and has good head control we’re happy for him to be on his front
If he's getting himself in that position then he has the head and trunk control to move should he need to. Always put them to sleep on their back, but if they turn over that's ok
If he can’t roll from front to back then PERSONALLY I wouldn’t let him. My thoughts are that when baby is really tired, their bodies are heavier and it’s harder for them to move.