I would also like to add that in my experience, unfortunately, "asshole"-like behavior isn't going to change when the source is a person in authority or a person close to someone in authority.
I've been at two separate jobs where I encountered people like this. (Thankfully, I did not have to directly work with them - that would have been tough). Coincidentally, both had the title of "Senior Architect" or something like that, and both were extremely bellicose and condescending in their tone to a variety of people, both in person, on the phone and in emails.
In both cases, I knew of multiple people who had complained about the individual's behavior to management yet in both circumstances, nothing was done and the behavior continued. In one case, more than one person quit and specifically called out the offensive person in their "farewell" email. (This is not something I would recommend)
I eventually left both positions, for other reasons. In one case, during my exit interview, I was specifically asked by HR if I'd ever experienced any "difficult" behavior from the individual in question. I declined to give any details, as by that point it was clear to me that management not only ignored this behavior but condoned it as well. (You may not agree with my course of action) As far as I know, both of these people are still working at the same places, and I'm assuming nothing has changed.
This is unfortunately how many of these situations end up. My advice is to choose your battles wisely.