Re: "I teleport the criminal's gun out of his hand"...
If it's in a Focus, the "power" can be "dispelled" by damaging it or removing it physically from the wielder. That's what the Focus Limitation allows, and why it makes the power cheaper. No need to get all complicated in how to take a Focus away from a target.
Having said that, IMO it would be completely wrong to let a Teleport UAA remove anything other than an Accessible Focus. It's a game balance issue. You can't teleport Tony Stark out of the Iron Man suit, or the Lantern Ring off of Hal Jordan's(?) hand.
And if the target has put all 350 points into that one OAF gun, that's his own fault. And remember, even though it's a Focus, and the Teleporter (or a teammate of his) gained possession of the Focus, the can only use it if it's a Universal focus, and even then, only for a short time. It's not like it's also Independent.