It's based on data gathered from scientific instruments that are well-characterized and whose results are validated by being used for other findings. They're not administering a questionnaire to someone's microbiome and doing sample statistics on the results. They found novel RNA sequences in microbiome sample data using well-understood and repeatable methods, and confirmed that the RNA sequences seem to exist. You can repeat the analysis yourself and make that determination.
I think you're trying to draw a comparison here between two things of completely different category, and I feel like you might not understand how different they are.
Don't be a dick. It's totally normal to be skeptical and doubtful of some over-the-top claims. The onus is squarely on the person presenting the information to justify it. Your points about replication are accurate, but let's at least keep it to a pretext of civility.
The claim is not over-the-top at all though. They did a survey of funny RNA sequences in gut samples and didn't find anything that links them to known sequence from other organisms. Nothing spectacular was claimed.
I think you're trying to draw a comparison here between two things of completely different category, and I feel like you might not understand how different they are.