Looks like a really nice and useful initiative.
Suggestion to the owners of the SFD webpage
I would appreciate the SFD initiative even more, if on the SFD webpage you would "live by your own words".
Facebook and the blue bird are by no means free software, also not according to your definitions "free to study [how the program works]", "free to distribute [copies]", "free to modify [the software]", "free to access [the source code]".
So why not at least show the benefits and use FOSS social media alternatives in action?
If you need the momentum of the unfree social media, you still could do this additionally.