When we're dealing with someone who repeatedly have ignored advice, instructions and admonitions and continues to cause major breakage, then yes, it would be sugar-coating to write something similar to what you suggested.
The point is that the person in question was being rude and disrespectful by continuing to ignore the instructions he'd been given in the past, and repeatedly caused a lot of very real, very heartfelt anger from a lot of people over the time he wasted for them.
Pretending not to be angry over that is very much sugar-coating to me.
Now, there are nicer ways of being direct and expressing anger, but pretending there was no anger and no valid reasons to be angry would be flat out dishonest. And I really don't think the recipient in this case had any reason to expect any civility from Linus at this point, even if others might choose less direct language.
