It wasn't the answer she wanted, but it was still the best answer she'd gotten so far. She had multiple allies who would avow Captain America's trustworthiness, but she personally found it a little hard to trust anyone who thought mutants should be registered and tagged like criminals. (Not that she was biased.)
"I can't say I agree, but I appreciate knowing that the Avengers have plans in place regarding this. Though I certainly hope that 'keeping people safe' includes the mutants, too." Moira had reason to be upset about hate crimes--she'd had to rescue her adopted daughter Rahne from the hands of an angry mob. She knew first-hand just how bad things could get when people were scared. And it was the supporters of Mutant Registration who were telling people to be scared of mutants. Saying that mutants were dangerous weapons, even the ones whose only powers were to heal or protect.