Can a Spiked Gauntlet worn by a polearm-wielding Fighter allow him to do attacks of opportunity with it?

If a fighter is wearing Spiked Gauntlets wielding a Ranseur, does he threaten both the 5′ area around him with the piked gauntlets and the 10′ with the Ranseur which would allow him to make an attack of opportunity with either weapon depending on the distance of his opponent?

How does wearing a locked gauntlet interact with failing a disarm check?

In 3.5, wearing a locked gauntlet provides a +10 bonus against being disarmed. If you attempt to disarm an opponent and fail, your opponent can attempt to disarm you in response. So locking your weapon into a gauntlet directly mitigates part of the risk of attempting to disarm your opponents.

In Pathfinder, however, the bonus from a locked gauntlet is +10 to CMB against being disarmed. If you attempt to disarm an opponent and fail by 10 or more, you automatically drop your weapon. As your CMB never comes into it, RAW suggests a locked gauntlet provides no defense against this – yet removing a weapon from a locked gauntlet is supposed to be a full-round action!

This seems counter-intuitive, to say the least. Is this really the interaction between a locked gauntlet and a failed disarm attempt?