[Sano snickers, because yes, she's probably right, a teacher should presumably know better, but so should a parent. Yamazaki-san has been more-or-less asking for it and Sano can't bring himself to feel bad. Besides, it's not like he's known for being reasonable. Alright, most of the time he is, but there are times when he chooses not to be, because it wouldn't be a good thing in the long run. Because there are more important things than keeping face and sticking to the rules.]

Maybe, but I can't really say I regret it.

[He answers with a sheepish smile.]

Yamazaki-san deserved every bit of it. Besides what you're proposing is a little nonsensical and wouldn't lead to anything. A son sending his father a howler sounds more like a spoiled and immature brat. If a teacher sends a parent a howler, now that's where the fun starts.