I'd also add they shouldn't just post the link. Post a screenshot of the portion of the page that supports their argument. In the vast majority of cases where someone posts a link, the article, essay, etc. upon which they rely doesn't actually support their argument and often contradicts it.
I actually did check the links in the footnotes that mentioned Coristine and no surprise, there was no mention of an FBI investigation. Either he didn't click the links, or he did and knew he was wrong, so rather than just back down, he blocked me.
Many, many times, the people only read the headline and make assumptions based on headline and never read the article/page. They don't get headlines aren't written by the actual article author and that they're worded to get clicks or edited for space.