When my wife and I were dating, there was no “online,” so I can’t say anything about that. However, we met in a way that the OP would likely consider just as (or possibly even more) scandalous — we met on our own.
Personally, I fail to see what business it is of the OP’s how his friend met his kallah. And as for his kids, I fail to see what the big deal is. Is he afraid that his kids are going to find out that some people don’t use formal shidduch dating? Are his kids currently unaware that there are Jews that aren’t Shomer Shabbos? Is he going to keep that fact from them forever? If so, there is nothing wrong with him telling his kids “Yes, they met online, but that’s not the way we do it…”
I recall a poster on these boards a while back who told me that I was required to divorce my wife because we didn’t meet through a formal shadchan. When I refused, he told me that I should ask a shaila. When I told him that I’m not going to bother my rav with such a silly question, he accused me of cowardice.
The Wolf