The term jaywalking was invented (or possibly hijacked) by automotive lobbyists as part of a campaign in 1910s and 1920s to convince the public and the lawmakers that crossing streets outside designated points is bad and should be made illegal. Before then, it was generally considered basic human right to walk anywhere on a street. Whether you agree that jaywalking is bad or not, that's the history of the term.

Grandparent is saying that the term sideloading was invented in a similar fashion to delegitimize a previously completely normal way to use an electronic device.