I am about as libertarian as one can get, but there is a difference. A nutcase with freedom of speech is a diminished threat to a free society (there is the example of a Hitler, or any other charismatic, to worry about). But a nutcase with a gun is a different matter entirely, and I am quite ok with access to firearms being restricted for children, felons (real felons rapists, murderers, arsonists, burglers, etc., I don't mean our modern make believe felons), and the mentally disturbed.
No one on this forum advocates giving the same rights to felons(all the ones you mention are felons)mentally ill people. Instant background checks are fine with all of us. Telling us we have to have a permit to carry or that we can't carry outside of our homes are not alright with us.
You must have a boatload of new laws in mind to prevent such people from having knives, cars, or access to gasoline.