This is all a bunch of panic over nothing. For starters, legislation may have pass on some random pipe dream, but seeing that to fruition is a whole other thing. Stuff gets passed all the time that never sees the light of day, and this could easily be one of them.
To answer the question though. If it's truly a "monitoring system" that is checking the driver's BAC? Then no our trucks can't do that and it wouldn't be possible without physically installing the systems to check your breath. If you're talking about the ability to remotely kill the truck? Then yes they could technically do that now. If they can start it, they can kill it. It may take a slight code change/update but UConnect will allow you to remotely start it so I don't doubt they could push an update over the air to enable a kill feature.
As for police or other government entities killing your car remotely. That's a long way off, if it ever happens at all. Probably not in my lifetime. The biggest hurdle I see is the actual application of it. The officer/agent would have to know your exact system access to kill it. You couldn't do a "beam" as someone mentioned because you'd kill other vehicles in the area. Not only that but a beam would be so easy for nefarious people to duplicate and randomly shut down whatever car/truck they want to. Talk about easy car jackings. Just wait for the car you like to drive up, kill it, and walk up and take it. You wouldn't even have to be at an intersection or parking lot. Just a random road somewhere. With a risk like that, there would immediately be aftermarket options to block the beam. In which case the govt. beam would be useless too.
So long story short, it would have to be shut down very specifically (like UConnect) and an officer/agent wouldn't have access to that fast enough to be practical.
I think a lot of people over estimate the efficiency and/or effectiveness of the government. Anyone in the military or those who work for State/Federal government knows that the people at the top have no idea how boots on the ground work. They can say they want something done but it rarely goes as they planned, and never as quickly as they want it to.