Some more colour is that the OSM Buildings project didn't even ask permission to use the OSM mark. If they were a community project, this was permissible. If they were a commercial project, they ought to have sought permission from the OSMF.
Given that, it seems pretty reasonable to me that the OSMF's stance was basically: your name is your problem, if you think someone is infringing on it, it's up to you to enforce it.
The OSMF runs on a shoestring budget - something like $400,000/year, vs Wikimedia Foundation, which runs on $170,000,000/year. It would be a real shame if a potential donor thought this particular instance was a reason not to donate to the OSMF.
Given that, it seems pretty reasonable to me that the OSMF's stance was basically: your name is your problem, if you think someone is infringing on it, it's up to you to enforce it.
The OSMF runs on a shoestring budget - something like $400,000/year, vs Wikimedia Foundation, which runs on $170,000,000/year. It would be a real shame if a potential donor thought this particular instance was a reason not to donate to the OSMF.