The logo is currently covered by the license of the Fortran-lang website, and the uploader was likely not the copyright holder. However, I’m happy they did and the logo is now used all over the internet.
Also, I took the liberty to adapt @jacobwilliams’s design, and publish it under MIT on the website, as @certik explained, and perhaps this was not the cleanest way to do it either.
For assets like this, CC-BY may be more appropriate than MIT (I think easier to reuse but I don’t understand all the nuances).
Regarding shirts, it’s nice that somebody’s making them already. I consider the logo a public good and it’s only good that people can purchase and wear the Fortran shirts. And somebody can make a few bucks doing it.
But, it’d be nice if Fortran-lang can have their own “merch” to help fund development, like conference registration for students and similar. And it’s easier than ever to have an online t-shirt store. For example, Threadless Artist Shops provides a fully-featured and 100% free online store with on-demand merch printing where you earn anything above the base cost of the item. If anybody would like to take a lead on this I will be happy to assist. It’s something that’s been on my mind for a while but there are so many things to do. And I’d like to buy and wear Fortran merch while supporting a cause.