[Rob1968]

Quote: "First, additional legal sanctions will not dissuade someone who has momentarily lost his or her mind to pause and think, “Oh yeah, If I slug this person, there’s an extra penalty.”

Quote: "There is no evidence that such legislation works as a deterrent to emotional outbursts."

This statement is an extremely tranparent cop-out. By definition, and logistically, a deterrent cannot be tracked -- there is no data to analize if the targetted action has been thwarted/avoided - deterred. Simply, if it didn't happen, there's no way of confidently projecting whether it actually would have occured, if the deterrent factor were not in place.
One may say, "well, during such and such previous timespan, the occurence rate was X. And, a subsequent timespan, with the proposed "deterrent" in place, had a rate of Y, therefore, the "deterrent" was or was not successful."
However, even in retrospect, such statements are projections, and not actual supported data.

This is the fallacy of attempting to view law enforcement as a "deterrent", rather than an enforcement.

Any such legislation is only certainly in play as an enforcement. And if not on the actions of a perpetrator, it most likely would have a deterrent value and effect on future potential perpetrators.
But to dismiss the opportunity to sanction negative actions, based on the statements presented, is an affront to those injurred by the miscreant individuals.

Sports officials deserve better -- better representation by their legislators, better support by all parties involved, and much more respect for the services they render!