So I can take something out of someones hands that they are legally allowed to have and if they hit me for it I can retaliate with deadly force?
As I see it you can't conflate the steps of this situation like that. We have three separate actions, each of which must be analyzed separately. Potentially either or both of Skidmore and the officers might be charged, or potentially nobody would be.
First, the officers tried to take the camera. I have no earthly idea whether Skidmore had the legal right to have the camera and shoot footage under the circumstances. I would guess he did, but the County could (probably) legally have implemented a rule prohibiting filming. Assuming (for purposes of discussion) that they did, the security officers would likely have been justified in taking the camera.
Second, Skidmore punched and bit the officers. Assuming the officers had the legal right to take the camera, Skidmore would have committed assault and battery by punching them and biting them. A prosecutor would argue that even if the officers acted unlawfully, that did not justify Skidmore's use of force, and legally I think that argument is probably correct. The analysis becomes somewhat complicated since they were trying to take something off of his person (and thus touching him), but my sense is that the use of force to defend his property would probably only be a winning argument in the minority of states that permit the use of force in defense of property.
Third, after Skidmore punched the officers, one of them drew a weapon and fired it (potentially an accidental discharge - that is not clear - but in any case drawing the gun seemed clearly intentional). Assuming that was an intentional firing, the officer would have to justify his use of force by showing that he reasonably believed Skidmore was likely to inflict death or great bodily harm on himself or the other officer. No idea where a fact-finder would come down on that, but the fact that Skidmore bit the other guy in the face would not work in his favor.
The situation is not without its complexities, but in any event I think it's appropriate that Skidmore be prosecuted. If a jury sides with him based on the facts of the case, so be it.