Not to be a menace, but do you have a specific source on the claim that that it collects telemetry on sideloaded books? In the Github link there's a line that says it "locks down telemetry" without elaborating further, I couldn't see anything else about it in the docs and a quick web search doesn't bring up anything about Kobo collecting telemetry on side-loaded books.
It'd just be nice to properly verify before I do anything.