I think these and your other thoughts get to what I am saying. Putting out impossible-to-verify information and then saying "it's just a rumor, so if it's wrong, it's wrong" deserves some sort of response or criticism. Every false rumor erodes our potential trust in them.
For a fledgling site/podcast to start off by parroting rumors on random MMA instagram accounts with no attribution is akin to circling the drain for me, just an echo chamber of false information starting with "sources say" or "I heard". Now, I know news, so I am fully aware that disclosing actual personal sources can be difficult and risky. When it comes from external sources or those that have posted it publicly but not on a platform that everyone can see it, however, it should be the rumor spreader's duty to say where they originated from. Otherwise it's just irresponsible. It isn't even a lot to ask, either.
It makes things worse when the rumor spreader says something like "you heard it here first" when in fact it did not originate from them and was merely reposted by them. It would be like the first person to post a breaking story from MMAFighting on TMMAC saying "well you heard it from me first." It doesn't work like that. If that person actively pursued the information in a journalistic fashion (speaking to camps, reaching out to managers, hearing from fighters, etc.) it would be one thing and then it would be their scoop, but when it's just information gathered by trolling (the fishing definition) random instagram pages for stories, that's not reporting at all. That's just mmaimports with another name.