I agree with everything the article said about post-9/11 hysteria and the exaggerated fear of knives. But that's a problem of measure, not of principle. If everyone used knives as tools only, there would be no occasion to limit their presence in public places like planes or stadiums. Since they are used as weapons, there is such occasion, and it would be irresponsible not to meet it.
As for the freedom issue, I do think the freedom of the many to live without harm to limb and life may make it advisable in certain cases to limit one man's right to carry whatever weapon he likes.
If you ride into Dodge City and the sheriff confiscates your gun because there's been too many gunfights and armed robberies, he doesn't have to be a liberal. But he complies with the liberal principle that individual freedom stops only, but necessarily, where it curtails the liberty of others (and then it's a question of balancing, mere hysteria shouldn't outweigh our reasonable interest in EDCing a non-combat folder, of course.).
Otherwise, you get the tyranny of the strong.
Personally, I think that's the historical watershed between
the conservative notion of freedom (the personal freedom to do whatever you like... at least if you're a WASPish heterosexual conservative man)
and the liberal understanding of freedom or liberty (civil rights and freedom from oppression/discrimination/curtailment of choice for all citizens even if non-white, of a non-male gender, of non-heterosexual orientation, of non-conformist views, or - unarmed / a sheeple
Just my two cents,
no offense,
thanks for not killing me

t.