Why would matter exiting a wormhole be more energetic? It would be less energetic.
In a blackhole matter enters, undergoes E=mc^2 and is re-emitted as conveniently detectable radiation. In a wormhole, matter potentially traverses the length and remains as matter - which means no gamma ray bursts, just whatever heat you pick up from jostling around with all the other matter that might be doing it.
The gamma ray burst energy doesn't come from matter to energy conversion. Recent studies found they consist of normal matter (atomic nuclei). This gets accelerated to near light speed by conservation of momentum in the accretion disc, and the frame dragging effects of the black hole geometry.
Light doesn't exit a black hole at all. Hawking radiation consists of twin pairs of photons that form just outside the event horizon (geometric energy to matter conversion). One falls into the black hole, the other escapes.
Matter falling into a black hole will gain a lot of kinetic energy from the gravitational potential alone, which counters light speed at the event horizon. And on the other side, if stuff can get out again, there can be no event horizon, so the potential well would be less steep. Classic worm holes even are theorized to have a repulsive gravity on the exit end, so matter would be accelerated even more.