Commenters have been reasonably accusing the researchers of bad practice, but I think there's another possible take here based on Hanlon's razor: "never attribute to malice that which is adequately explained by stupidity".

If you look at the website of the PhD student involved [1], they seem to be writing mostly legitimate papers about, for example, using static analysis to find bugs. In this kind of research, having a good reputation in the kernel community is probably pretty valuable because it allows you to develop and apply research to the kernel and get some publications/publicity out of that.

But now, by participating in this separate unethical research about OSS process, they've damaged their professional reputation and probably setback their career somewhat. In this interpretation, their other changes were made in good faith, but now have been tainted by the controversial paper.

[1] https://qiushiwu.github.io/