I don't even really blame someone like that for lying about it (because - really - what a stupid thing for anyone to do). The thing that gets someone like that "points off" in my book is that they're in office. It doesn't take a "big genius" to figure out that sending pictures electronically isn't the most brilliant thing to do, and is likely to result in someone's at least telling one did it. And yet these clowns do this stupid stuff and then try to pretend they didn't.
I mean, either do the stupid stuff and just own up; or else don't do stupid stuff and you won't have to worry about anyone finding anything out and making a laughing stock out of you (at best). So, to me, someone who can't or won't grasp that simple concept of either do what you want and own up, or don't do stupid stuff at all; is either too much of a little idiot to be having a say in office, or else is so much of narcissist he thinks he can do stupid stuff and that everyone else is too stupid not to be fooled by his lies.
So, basically, I don't see it as being about what he did or even about his lying about it. It's about his showing a number of signs that he's yet one more clown who ought to resign (regardless of his party).