Well, the one of the issues is that that claim is not “given”; and no one yet (to the best of my knowledge) has come up with even a single court case on the subject.
Which makes it probably much less problematic than, say, allowing/promoting image=* or wikimedia_commons=* of the outside of the building, which is much more likely to be potentially problematic (e.g. see Wikipedia’s Freedom of Panorama for list of some more popular court cases).
Single image often isn’t suitable; that’s why MapComplete uploads multiple images with multiple tags (see example in the original post which has 2 pictures for menu, e.g. image:menu:0 ).