Be prepared for a long rant
For starters, there was nothing wrong with making magic maps that marked out every single corner of the school, I dare you to find a rule against that
Yes, I can understand Remus betraying Dumbledore’s trust and his friends going animagi with him was not the greatest, but without that, I doubt that Lupin would survive through his 7 years without getting serious depression.
Then, the Snape being the Half-Blood Prince. He did not ask anyone else to call him by that dumb and arrogant name, we can see so by when Harry asked Lupin who was the Half-Blood prince, he was clueless. Undoubtedly Snape had told no one about his secret nickname.
And finally, how in the name of lord is this related to nerds, a term to define the person being called is someone that spends all his day studying and doing nothing else?