I think a less charitable explanation is that they hope this will pressure developers into making their license info more consistently available to the advantage of everyone -- like how Google adjusts its search ranking algorithm to punish certain kinds of behaviour/problems.
Yeah, that's also a valid point. I've contributed license PRs to several projects, just so that the next person doesn't need to trawl through the readme or source code to find the one line that specifies the license in the most ambiguous way possible.
... which I would be perfectly okay with.