The idea one should be properly and fully trained to operate equipment is completely sound and valid.
However, when you use a system that looks like the usual but actually operates differently, proper training, understanding, and experience become vital to safety.
I worked for many years in an old chemical plant that used red and green lights to indicate the status of operating machinery (pumps and other things). HOWEVER, that plant had a standard completely opposite what people were used to.
Most things are made so that red indicates "stop" and green means "go". Or red means danger and green means safe. In that plant, a red light meant the pump was on, and running, (and therefore dangerous) and green meant "off".
New operators often thought in terms of traffic lights (red=stop green=go) and had to be carefully trained to remember (at all times!) that in that plant the lights meant just the opposite. This could (and did) result in some confusion. One system was very confusing to new people, an upgrade had been done and the new pump controllers on that system used red and green buttons that lit up. The manufacturer made it so the lights worked the usual way, but we had to have it reconfigured a bit to match the rest of the plant's standards. So what it turned out to be was that when you pressed the green button to start it, the red button lit up. And the green button lit up, when you pressed the red button to stop it. IF you understood it, and knew the why's behind it, it made sense, but, UNTIL you did, it was confusing.
Firearms use several different systems, some use lever up for safe some lever down. You have to learn to use what you are using correctly or its going to be a problem, potentially a very serious one.
There's nothing "wrong" with Binary triggers, but there is a different level of risk possible because they work so much differently than the usual triggers.
People who know how to properly operate the machinery are not the problem. People who think they do, can be. And this is a situation where even one moment of forgetfulness or inattention can result in an unintentional discharge. And while this is true in general with all guns with things that work in uncommon ways, the tolerance for mistakes is much smaller.
Put someone who just learned to drive in a formula one race car or a tractor trailer rig and they're going to have problems, because while they know how to drive, they are drastically undertrained for those very specialized vehicles.
As to the 86 Hughes amendment, as I understand it, it was intended to be a "poison pill" to kill the proposed FOPA, and there is still argument over if it was actually legally passed under the House rules. It was declared passed, and so was included in the FOPA. Reagan signed it into law, in order to do the most good for the most people accepting the bad so as not to lose the protections in the main bill.
Personally, I agree, it is an unacceptable infringement of a Constitutionally enumerated right. But unless Congress (and the Pres) create a law which repeals it, or a Supreme Court rules it unconstitutional, its what we're stuck with.