I wish I could tell you, there is something to be said about 1) being live with no recording so records of dissent dont exist and 2) like the other commenter said slow government response
I suspect it's a lot of small things and social network multiplicative effect
So, this is an unencrypted (not end-to-end at least), intercept-ready chat network that was popular among (a) people with social status in the US, who might be of intelligence interest (sc. Elon Musk), and (b) people in a nation state that is definitely of interest to US intelligence? Is that right?