I was surprised to find that this group doesn't automatically accept membership requests. That does not seem to be in the spirit of free / open-source software.

Personally, I automatically reject groups that don't automatically accept new members. It feels too much like snobbery. How on earth can you even know whether you want someone as a member, if you've never even met them?
I am a big supporter of FOSS (or as I prefer, FLOSS - Free, Libre, Open-Source Software). It's a shame this group doesn't take on new members automatically.