Earlier quoted context omitted.
I think the issue is that the administration is in an adversarial relationship with China. Risky to allow a foreign power have a kill switch on critical infrastructure.
Just to clarify: We accept the security risk of kill switches in networking equipment, smartphones, laptops, servers, clouds, processors, bluetooth firmware and nvidia driver blobs, but we draw the line at civillian cars? And in contrast to the listed items above, for civillian cars you can choose from dozens of countries who produce them. And if you cannot accept security risk of owning a "kill switch" car then you…
The scale of car travel plus the inherent kinetic energy involved make a correlated risk particularly likely to lead to a mass casualty event. There are very few information system vulnerabilities with that magnitude of short-term worst case outcome.