There are many other projects which the FSF provides support for to further the goal of spreading free software and picking at one for presenting work they're proud of strikes contrast with the purpose of the conference.
[1] https://kristoff.it/blog/the-open-source-game/
[2] The Free Software Foundation (FSF) is a nonprofit with a worldwide mission to promote computer user freedom.
What should the FSF have done to do a better job? It's easy to say that some entity hasn't done enough without being in the same position and without providing an alternative solution.
We at the Zig Software Foundation for now are doing a reasonably good job at supporting our FOSS project by paying our contributors and by being as transparent as we can with the public (eg we're a 501(c)(3) non profit organization).
Note, there's nothing wrong with marketing and providing courses (something which the FSF also provides), it's just the act of promoting it while complaining about another organization not having "done enough" that has done much more within this space over the years.