Rather than jumping into a “revert / unrevert” loop, I’d try and have a conversation about what it is, is it verifiable, etc.
The comments on the deletion changeset say “please don’t delete it because it is given as an examle of a type=superroute relations in the OSM wiki” which doesn’t seem like a good reason not to delete (the wiki should just pick another example).
The website seems to be this. I could create a similar route tomorrow based on existing national routes and claim that that too “exists”, but I’m sure that other OSMers would claim that it’s not verifiable. What’s different about this one?
An adjoining part in France is here. The last status in Belgium was disused.. Perhaps, if it can be verified, the top-level relation should be reinstated with a gap for Belgium?