I'll pass no comment on what may or may not have started the emails - there's only two logical options: 1) He was/is looking or 2) He was looking at some other gentleman's material and is now bombarded with spam as a result.
I met Mrs Rockingit on an on-line dating site (six-ish years ago now, married for three) a couple of years after divorcing my first wife. And one thing I'll tell you is that 'unsubscribe' doesn't mean much to these sites! Both of us still get no end of spam and 'xyz has messaged you' type fishing emails, and we occasionally joke about it in order to keep things in the open and trustworthy. Occasionally, we'll even have a look to see if we recognise the person if they claim to be local (which probably doesn't help in the spam mail dept!).
My advice: it's between him and his conscience alone, you don't know the exact circumstances and you might end up starting WW3 inadvertently, albeit with the best of intentions. Keep an eye on how other things are with your mum, instead.
