Vacuum production of virtual particle pairs cannot violate the uncertainty principle.
Since you were talking in terms of partilces of gravity or gravitons, I continued the discussion in that vein. It appears that you mix up Einstein's theory where there is no gravity field or gravitons with the particle description of the same.
In Einstein's theory space is distorted by mass. Nothing else happens accept masses are accelerated towards each other includong the mass of a black hole. This theory is dual to the particle theory of gravitons. In the particle theory, the gravitational field is propagated instantly by virtual particles that travel at infinite velocity, so to speak. As such they propagate thru the event horizon.
Just think of it. If that were not true, then we could never detect a black hole. They would simply disappear from the universe. They could not affect the motion of the stars surrounding it.
My personal opinion is that mass is converted into the unified 26-d field within the so-called singularity of black holes, and new completely undetectable uniuverses spawn from the unified field in agreement with Smolin an described in THE ELEGANT UNIVERSE by Greene.
Perhaps the loss of black hole mass could some day be measured. However, it might ne that the highly energized unified field has the same equivalent mass. But the creation of a new universe should involve some loss of energy.