What evidence could he give without doxing himself ?
This is almost the same as "I was talking to someone about wanting to buy a gaming PC then I saw ads for gaming PC. They must be listening to my conversations". Nah, some people got told to figure out the patterns of people who go on to buy a gaming PC and someone figured it out. Just like how LinkedIn, TikTok, Instagram, figure out people you may know because you share a data point or two.
having my kids be seen 100 random viewers world wide is one thing, having the same video shared with all my neighbors is quite another.
there are enough examples of nosy neighbors in the US calling the police on things they don't like. look up free range parenting right here on hackernews.
noone is going to bother about a few kids filming themselves spraying graffiti at the local park, except some people who live at the park.
if an algorithm amplifies local activities to everyone around, then the wrong kind of people will find out.
it's the very definition of gossip that is being facilitated here. the assumption that when something is interesting for a pew people, it's probably interesting for everyone else in the area.
it was probably a similar algorithm that motivated people to turn into lynch-mobs in some places in asia.
it's likely this kind of realization that spooked the OP.
Who are the wrong kind of people?