seems extreme. one unethical researcher blocks work for others just because they happen to work at the same employer? they might not even know the author of the paper...
Low trust and negative trust should be fairly obvious costs to messing with a trust model - you could easily argue this is working as intended.
The objectionable part is that the group allegedly continued after having been told to stop by the kernel developers.
In typical grey hat research you get pre-approval from target company leadership (engineers don't know) to avoid charges once discovered.
If you read the research paper linked in the lkml post, the authors at UMN state that they submitted their research plan to the University of Minnesota Institutional Research Board and received a human subjects exempt waiver.
https://grants.nih.gov/policy/humansubjects/hs-decision.htm
for q1, the study collects data like observations of behavior, so we must answer yes.
for q2, none of the exemptions apply - it's not an educational setting, they're not sending a survey, it's not an observation of the public - they're interacting, and it's clear that these interactions are not benign - they have clear impact on the community. None of these exemptions apply.
Based on this flow, it's clear the study involves "human research".