A decision about how the public consumes Wikipedia content (e.g., Media Viewer) is an editorial decision,
and it's one that the WMF has chosen to
make unilaterally. WMF has furthermore moved to give its staff rights that facilitate unilateral behavior in the future. But to the degree that Sue Gardner's policy remains in place (and I'm assuming it does), the WMF's position is that any problematic actions taken by individual staff should be subject to community processes.
I think this is a misunderstanding. Erik's actions are pretty clearly made in his capacity as a WMF senior staff member, and it follows from that fact that the WMF regard this a decision that it is (at least in the final analysis) one that is theirs to take (that is to say, not "editorial"
Arguing that Erik ought to be sanctioned on the German wikipedia for doing his job is, being as kind as possible, futile wikilawyering.
If you disagree with what he is doing then some appropriate courses of action involve speaking to Foundation ED or their Board. There are many other inappropriate courses of action that are being pursued as well, though.
Chris