I understand that you'd LIKE to have it be that way, as you said, but I don't think that's the case. I was under the impression that making guns easier to disarm was a balance issue.
And, frankly, YES, I DO see a gun as easier to disarm than a baseball bat. A ton easier, in fact. Heck, going halfway to meet you, I can even see a gun that's just been used to club someone as being easier than a gun that's just been used to shoot. Holding a gun in a "ready to fire" position leaves it extremely vulnerable in your hand. The position of the hand and fingers used to steady and fire a gun is far different from the "Hold it as tight as you can and swing hard" position that someone who's just clubbed it is going to use.
Counterquestion for you. You seem quite firm in your belief that the gun is ALWAYS a melee weapon for purposes of disarming. Please explain how I, with a baseball bat, can swing at the wrist of a bad guy with a gun, fail my opposed disarm check, and be disarmed in turn, as the bad guy is perfectly within his rights to do. In your game, by the rules you're using, this will be a pretty common event, and people will have their baseball bats and longswords knocked to the ground by the impressive disarming power of the handgun.
Also, please explain why they said in the rules for disarming ranged weapons, "The weapon gets a +2 bonus if held in both hands"? What ranged weapons do you see that happening with besides guns? Do people in your game run around with grenades clutched in both hands for long periods of time? The rule is pretty much written in there to make "Holding a gun in both hands" an attractive prospect. In your game, however, people will be disarming each other with their handguns, so that's kind of a moot point.
-Tacky