Probably a bad clutch switch. I had that happen on my 2014 and I sprayed some contact cleaner into the switch and it started working properly again.
What tdh says. I've had two go bad. Easy to check if they are good or not though.If you have a multimeter you could set it to ohms and verify it's working when you pull the lever.
Yeah, good point. You're right. The sidestand switch wouldn't really have much to do with it in this case.I was assuming once he starts it in neutral and then puts it in gear it stays running when the stand is up. If that's the case it wouldn't be the sidestand switch and would most probably be the clutch switch. However, if it dies when he puts it in gear after starting with the sidestand up, then yes, it would be the sidestand switch. But, he wasn't fully clear on that.
It's the aftermarket levers. You have the adjustment too close to the bar. The lever is hitting the clip-on before the clutch switch is released. The adjustable aftermarket clutch levers don't really offer you much adjustment because of this. That and the clutch is likely dragging somewhat now too.
There's a reason the stock lever is not adjustable. Set your clutch lever adjustment to the maximum setting (farthest from the clip-on) and try it again.
If that doesn't do it, then the clutch switch and sidestand switch should be checked.