yeah, I'm on the fence about this one. I can certainly understand the younger X-men's anger, but Sam and Roberto's defense of Illyana is equally understandable. Of course, the appropriate response from Sam would be to talk the kids down calmly rather than threatening violence and also telling Illyana not to make the situation worse by being antagonistic. Completely letting her off the hook gives a bad impression.
"She's got more of a right to be here than any of you" is a universally stupid line to feed to a bunch of kids who've lost more friends than the New Mutants ever did and have suffered traumatic experiences equally as bad as anything the original New Mutants did back in the day. Sam's protectiveness is understandable. But I still think he was acting like a dick.