Why are all the people so protective of Data? He didn't take Pulaski's behavior towards him personal.
Pulaski is hardly the only person to treat Data like that. And she came to grudgingly accept him somehow in later episodes. Pulaski stands up to Picard and speaks her mind. If that's mean for you, I can live with it
She came to ``grudgingly accept him'' by the end of Elementary, Dear Data. That's like four episodes in. By mid-season she liked him. By the end of the season she was probably his biggest booster aboard ship.
The progression of her character doesn't draw much attention to itself --- obviously, or people wouldn't be consistently wrong about this --- but it's one of the most surprisingly natural character developments Next Generation ever did. Pulaski figured she would have nothing to like about this robot that thinks he's a man, until she actually, you know, interacts with him and discovers she likes this relentlessly likable fellow.
Perhaps you're right. As I already said, I don't remember if her attitude towards Data better during season 2, so I'm willing to believe you when you say it did.
So in my opinion, that would leave no one of the regulars who is mean.