To be honest, this whole plot line of Snape trying to get students to realize that Remus is a werewolf, and then later straight up telling them, is the thing Snape did in the series that bothers me the most. Because who are you to out someone else’s highly stigmatized medical condition? It would be one thing if he did it because he thought Remus wasn’t safe to have around the students and he thought outing him was the only way to get him to leave the school (still not an acceptable way to handle it, but a little more justifiable). But that’s not implied anywhere in the book. Snape never indicates that he’s worried about Remus’s lycanthropy.
I get that Snape thinks Remus was involved in Sirius’s prank in sixth year. And yes, that was a horrible prank and it was not in any way okay. But
1) that was seventeen years ago. And if you expect people to forgive you for the things that you did around that age (aka participating in what amounted to a pro-genocide cult), then you need to offer them the same privilege.
2) it’s not acceptable to reveal someone’s private medical condition, particularly when society has a massive negative stigma against it, without a safety reason. Queen JK has said that she wrote Remus’s lycanthropy as a metaphor for HIV. In what universe would it be acceptable to tell a teacher’s students that their teacher has HIV just because that teacher’s friends bullied you in high school?Snape may have been prompted to set this assignment by the way Remus had Neville handle his Boggart, which might have reminded Snape of being bullied by the Marauders. Bullying is bad, yes. As someone who was bullied throughout childhood, I’ll be one of the last people to deny how hurtful and damaging it can be. But stigmas like the ones surrounding lycanthropy in the wizarding world make it hard for Remus to get a job, get housing, and even interact with large portions of society. Being outed as a werewolf has a giant and potentially permanent impact on his quality of life and his ability to meet his basic needs. Which in turn restricts his options for what he can do on a full moon (unless the Ministry of Magic pays for Wolfsbane Potion, and it doesn’t sound like they do), which then puts other people in danger. If Remus wants people to know, then he is obviously free to tell them, but it’s not someone else’s decision to make for him.
3) it’s especially not acceptable to reveal someone’s private medical condition because society has a massive negative stigma against said condition. This, to again go back to the metaphor, is the equivalent of telling a teacher’s students that their teacher has HIV because you know that many of the students and/or their parents will have a negative reaction to it. This is treating a person’s illness like a weapon you can use to attack them from the outside, as if it’s not bad enough already that the illness is attacking them from the inside.
Snape did good things. He wasn’t all bad, and, yes, he had a hard life. But, in my opinion, none of that excuses this, particularly not coming from an almost thirty-four-year-old man who should have known better and been beyond such pettiness at this point in his life.