I am always amazed how easily Americans are scared if they hear about an event of civil unrest in the world. These days you could be at the wrong place at the wrong time anywhere in the world, if you are unlucky. Chances are that it's quite rare to be one of the unlucky ones.
There is another quality of unrest in European country's riots vis a vis real riots in the US. The rioters have usually no weapons aside from stones, sticks, hammers and may be some little self-made molotov cocktails (to set fires) etc. It's targeted at things to destroy for demonstrating they are angry, it's not targeted at specific persons or a specific group of foreigners.
It's certainly not targeted against Americans this time around. It's targeted against the French elite and policy makers or just targeted at adults and for the media coverage and attention, I would assume.
Well, I shouldn't make that remark. May be it's more serious, but I wouldn't see why your son would be close to the street fighters while participating in a tournament?
Same thing here: car burnings and other arsons happen in very specific areas: low income housing projects outside of the main cities (mostly concentrated around Paris), the "outer cities" so to speak, that are far away from the main touristic places or urban centers.
Total number of fatalities so far: I haven't checked the exact number, but probably less than 5 (including the two kids who were electrocuted in a power substation). The arsonists avoid confrontation and hide from the police. Their goal is to make the headlines on TV (and boy, does it work well..), their 15 minutes of fame every day. This is the "Reality TV" generation.
The other 99% of French territory is just going about their business.
Your son will be safe in Lille, at least much safer than in most large US cities, and if he's been there all summer, he already knows where to go and not to go.
BTW: I can't locate any travel advisory for France. The State Department "Current Travel Warnings" mentions the usual countries, the only European one being Bosnia-Herzegovina. Europeans think a hundred miles is a long way. Americans think a hundred years is a long time.
