Greg, this is where you have to read ONLY what UL says ... and not jump to conclusions. Oddly enough, this exact situation is used as an example in the UL books regarding the modification of listed equipment.
The use of this bar does not automatically 'void' the UL listing. As UL takes pains to state, UL has no way, without examination by them, to determine whether the modification voids the listing - or not. It may be perfectly OK; I suppose that all you can say is that a modification MAY effect the listing.
So ... all you have is "might be a violation," and not "there IS a violation." It's your call. Were it my call, I'd praise the guy.
As UL is also very careful to say, it is the responsibility of the AHJ to determine the acceptability of the modification.
