Well, he didn't say" Your REAL Family" he just said "Family" I didn't take it as passive agressive, but I can see that.
True. Or maybe their intentions are actually pure. We won't know until further into the story.
I took it as a friendly reminder that Scott was simply reminding the Richards family that Franklin is a mutant and we are his family too. I'm not sure if I would be angry at that because Franklin doesn't know he's a mutant.