It’s sort of alluded to but I suspect journalists get a whole lot of false tips from various mentally unhealthy folk, which perhaps appear much like Williams’ in this story.
Yeah, being contacted by someone who’s on a bespoke undercover mission in right-wing militias is huge. Being contacted by someone who’s says they are is another matter.
We don't know how the initial attempts at contact were presented. I can see it being extremely difficult to get someones attention. If how seemingly technical people ask for assistance on net forums is any indication, unless has someone has the skill of a reporter in presenting information, a string of signal messages with, "contact me, I have important information on XYZ" isn't going to cut it.