Fly-by-wire does not mean what you think it means here. Fly-by-wire means that the control surfaces are not connected directly with cables. It does not have anything to do with automated control such as a flight computer. To be able to ditch in the Hudson the flight computer was not being used.

At least in Maryland and Illinois the wiretap laws have been ruled unconstitutional. So I would hope that GM's lawyers would first research the issue as they could run into the opposite of what they intend. In this day and age they can be looking at legal action from owners if such a feature is disabled in a state where such laws are unconstitutional. http://articles.chicagotribune.com/2014-03-20/news/chi-supreme-court-eavesdropping-law-20140320_1_illinois-supreme-court-illinois-eavesdropping-act-cook-county-jail