Here's a possible argument for why an automaker would cheat on emissions but not want to give the impression of self-driving.
Violating emissions laws will get governments suing you, but individuals often see vehicle emissions as a nuisance, not the end of the world. Governments, however, have a vested interest in keeping the economy running, which means not hitting automakers too hard, unless they're not contributing much to the economy that that government is responsible for. (Which is why the US government hit VW as hard as they should have, but Germany's dithering on whether to hit them much at all.)
Crash safety issues, on the other hand, are the end of the world for many individuals. As a result, they'll cause personal injury lawyers to seek blood, and they have no vested interest in the car company's continued existence. Consider the general aviation industry, where over half the price of a light plane goes to pay lawyers and insurance companies to defend against pilots' and passengers' families suing the manufacturer. Giving the perception of self-driving when the system isn't able to do that - and Autopilot is not - could be considered negligence on a manufacturer's part.
(I am not a lawyer, though. And I invest in TSLA despite my concerns about Autopilot. Note that I think Tesla could massively improve Autopilot's safety through technologies like the eye tracking that GM's Super Cruise system uses, too, to ensure that the driver is paying attention.)