And if Seamus had know that she would say that then he would keep protecting her. But right now they were in an unsafe environment. He wasn't going to let the Queen die because they couldn't find her son and grandson. Not on his watch.
At her cry, he turned around, crying out a protego to get a shield up before using charms to get the attacker at bay. Though he really wasn't sure how well he was fairing in the process.