Why go easier on weapons in general? While I think the premises and conclusions are rather questionable, you can at least make an argument that armed passengers could prevent a takeover of the airplane. But that presumes that this is necessarily the goal of the suspect - if Richard Reid had his s*** together, instead of trying to light his shoes with a pack of matches, it's difficult to see how his fellow passengers could have prevented him from blowing up the plane, armed or no. In that case, the best solution would seem to be to prevent him from boarding in the first place.
I don't believe I said that an armed passengery (yes, I just made that word up) would provide absolute safety against terrorists. I said it would provide additional safety. I agree that it would be best to keep him from boarding in the first place. But two things should be kept in mind: 1. Our "professional, federalized" airport security service failed to catch him - maybe because they were focusing their efforts in all the wrong places? and 2. It was the passengers who stopped him. So my overall strategy I think would be to further empower the latter, and to reform the former. It may not provide perfect protection, but then I don't think anything realistically can. It will, I think, provide better protection, as well as less hassle all around, even for the people who are profiled.