Yes, this is really difficult problem. From my experience, doing these three things when being critical puts you in the not an asshole category by the vast vast majority of people: 1. don't raise your voice or yell, 2. don't insult people personally (say "this code is bad" instead of "you are bad for writing this code"), 3. if it is your first time critiquing someone, explain your style of criticism and note that it should not be taken personally.
Of course, there are very sensitive people, and you can't please everyone, but in my experience people will try to be accommodating if you tell them your situation.
You're getting downvoted, but there is some truth to this. Many years later, when I was much more confident in my career, I took a very well paid but short contract gig with a horrible boss. I found that the best way to deal with his outbursts was to find them funny. Screaming at the team for not making an arbitrary deadline he never told anyone about -- there's something comical about that. HOWEVER I would never want to work with someone like that for more than a few months.
In the situation with Felleisen, I was around twenty, in a new city, new to the academic world. The student I mentioned was one of one or two female students in the entire class and already unsure of her place. Asking people in those situations to not take insults from their professors, famous people in the field, gatekeepers personally is to ask them to overcome human nature itself. I would describe that as a hard problem.
I want to distinguish between a hardass and an asshole. Some people are conflating them, and the middle section of their Venn diagram is not empty, but they are not the same thing!! There are more choices than cuddly "everybody gets a trophy" snowflakes and calling children worthless morons! Everyone should have a hardass professor or a hardass boss at least once in their life. These people have high standards and push you, they don't accept excuses. You learn to work. They don't insult you or throw a fit, though. Hardass professor: "This is not good work. These are the reasons your work is bad. I expect better from you next time." Asshole: "This is not good work. These are the reasons you are a stupid and worthless person."
On the other hand, there are drill sergeants and similar situations. I don't know how to work them into my model. Some people seem to thrive in an environment like that. I wonder what the difference is?
Years ago I was planning on entering a PL PhD program until I met Felleisen. He yelled at me, insulted me, and I left nearly crying. That was the last straw that led to me leave academia, and I never came back. A young woman I know switched out of her computer science major after taking his class and said she still had nightmares about him. Another person I know worked with him on a project as a student and said half the team dropped out due to his behavior. He would call the remaining team at 2am or 3am to yell at them sometimes (according to my friend).
I'm not sure how I feel about this coming out. I don't get the feeling that he's doing this on purpose. I've heard from people close to him that that's just the way he is and you have to get used to it. At the same time, he's been making people feel like shit for decades. Academia used to be a place for misfits who don't understand social conventions. What if not understanding social conventions comes off to others as bullying, though?
Racket could be better off without him. He might be brilliant, but he is so difficult to work with, he hurts his own project.
Of course, there are very sensitive people, and you can't please everyone, but in my experience people will try to be accommodating if you tell them your situation.