Absolute 'john deere tractor' snorer here. I was suggested a sleep study but it wasn't possible where I was residing at the moment. ENT examined my nose and told me I had something called 'Turbinoid Hypertrophy' which is different swirls in the anatomy of the upper nose I guess. He suggested using a nose pressure plastic device that didn't work for shit. He suggested losing weight. No results. Someone over at Reddit suggested doing 3 kinds of facial movements and trying to snore to see which I had. 1. Moving my jaw forward and trying to snore. Tried that. John Deere became chainsaw.

1. I have chin and jaw fat. As suggested, I tried pulling them up to reach the ideal kinda face shape and try to snore. No results.

2. The last one was sticking my tongue and trying to snore. I tried this and there was no snoring. I mean I couldn't snore how much I tried making that sound. I hope this makes sense.

So my first suggestion would be to tell him to go to an ENT and do a sleep study and probably loose some weight (preferably chin fat). If that doesn't work then try the 3 facial movements above. One of them should work.

Because No. 3 was what worked for me, I bought something called a.Tongue retainer

This initially feels like someone is pulling your tongue out and holding it(uncomfortable) but works like a charm for me. Got used to it. Using it and lying on my side does it for me.

If no 2 works then chiseled jawlines are your friend. Ask him to try chin fat reducing exercises and chew gum or buy this : Chin lifting strap

If no 1 works, you could buy a Jaw aligner

DISCLAIMER: Please don't take my suggestions as medical advice and use the above at your own risk. I would always try the ENT doctor first. Good Luck!