Advertisers are after customers and will target whatever overlaps them. So either entire sites (e.g. because it's entirely about basketball), channels within sites (e.g.the basketball section of a sports site) or content keywords (e.g. any blog article that is about basketball) and can also narrow things down by region, age group and so on.
In this case, if you are seeing the ads and you know the guy involved then chances are he's just targeting the local geographical region and the ads are appearing where there isn't much competition so they are cheap - (there is a thing called an ad-auction that determines which ads show on any given page, the advertiser sets a "bid price" for what they are willing to pay per 1,000 impressions or per click.
The other reason ads are chosen is not because of the content of the site but because of what you have searched for and viewed before. So if you searched for his business then ads can show up.
I doubt he's be specifically targeting this site unless it was related to the business somehow (e.g. selling goods or services to JWs / exJWs). The content of the site isn't really monetizable so content related ads are rarely the things winning the bid auction which makes the localized or search-targeted ads more likely to appear.