I highly doubt the adversaries actually care about kernel.org in particular.

It's more likely that they're trying to scrape the entire internet, and cgit is just unfortunate enough to have autogenerated pages, where each page seems to contain text entirely distinct from its neighbors. This probably bypasses the scrapers' heuristics, which normally prevent them from getting trapped in a maze of twisty little autogenerated pages, all alike.

The way you normally deal with datasets at that scale is to move postprocessing (particularly expensive postprocessing) as late in the pipeline as possible.