If I had been sitting and waiting and someone told me “I see you’re angry. You’ve been sitting here for 30 minutes and that’s got to be frustrating. And it’s not the first time. Also, I can see how it seems like I think being with a client gives me permission to be late. I’m sorry you had to sit here waiting for so long.” I think I would have gotten up and walked out! The first thing he should have said was "I'm sorry!"
The whole validation thing just always seems to come off as a way for the offender to cover their own butt instead of owning up to an error. And if this is a recurring offense, the words are worth even less.