I’d argue that BY-SA prevents others building on your work and then license the result under a different license (either more open or more closed). You would not be protected from what happened here (re-licensing) any more or less than with the other licenses, because re-licensing is either illegal or meaningless: a license builds on intellectual property rights, so it’s only you as the holder of those rights that can put a license on it. The best case scenario for GBIF here is that there was no IPR to be had anyway so both the original and the changed licenses were meaningless. Either way, good that this is being solved. I think it is great that a forum post can lead to improving practices, kudos to all involved.
The reason that SA is not a part of the licenses GBIF accept is that the SA part refers to derivative works. It is very hard to define what derivative work of an observation would even be. (The photo has its own license, it’s not a part of the observation). A larger data set or database would not be derivative of an observation in it, so using it in a scientific paper would not affect the license of that paper either. So even if a fact would be copyrightable, the only practical effect would be some added confusion. Generally, more rules means more potential for work not being reused just to be on the safe side.
I personally like the idea of SA and other viral licenses, but not the consequences. It’s the most restrictive of the open licenses. CC0 says “go ahead, use this, you really won’t get in trouble” which is exactly what I want my data to say. Also, I want my data on GBIF so SA would never be an option for me here. (Side note: my pictures are CC BY, as receiving credit is not a right I can waive under Norwegian law. No one would get sued over not giving me credit, but I’m okay with reminding people in this way that giving credit is a good thing regardless.)
My own choices aside, I totally respect that others can have other goals with their data, and applaud anyone giving this thought and actually actively choosing a license :)