Yup, OP doesn't seem to understand that the Fediverse is still in an "early adopter" stage. For tech stuff, that's a demographic which is usually dominated by male tech nerds. I suspect the age range is more diverse than the OP claims. Though, I imagine it centers somewhere near the 25-35 range, as those will be the people with the drive and time to ~~engage in online mental masturbation~~ argue with people on the internet.

Also, the math will make the median age skew older. Each older person will have a larger effect on moving the average age up. For example, consider 3 people with ages 45, 20, and 18. they have an average age of of just a bit over 27. There is a lot of room for us old farts to drag the average up while there is only a small range for the kids to drag it down. There might be the rare 9-10 year old who has the wherewithal to make an account and comment. But, I don't suspect the user base will get all that much younger. Whereas, there's probably lots of late 30's and 40 year old users and some even older. Take those same three ages listed above and add in a precocious 10 year old and a 60 year old grey beard. The average is now just over 30. That older person had a larger effect on the average than the kid.

Also, age doesn't matter all that much. The important thing is that the early adopters are here and making content. Ideally, this will build out the site and others may follow (or not, not every trend works out). But hopefully, this will end up like the Great Digg Migration before it, which fed the Reddit beast. And we'll have something a new, different and maybe actually better this time.