Can they do the same thing now for Syncthing?

I agree with you, anyway there is a working syncthing fork active and available on f-droid : https://f-droid.org/packages/com.github.catfriend1.syncthing...

So it just goes to show that google acted in bad faith all along

damned if they do, damned if they dont.

You mean damned if they do but allow their own applications the unrestricted access, and damned if they later change their mind without stating any reason or change of policy due to public outcry but still hamstringing other applications that serve a similar purpose that can't get the same level of media coverage?

I mean, yes? This is exactly what happens when you put yourself in the position of a censor, especially as people's reliance on you grows and grows. It is fundamentally impossible to please everyone.