Dean had actually helped, during the crisis around September 11. When it had happened, a call had gone out to the magical community in New York, and he'd answered it to do what he could. Which, as it turned out, hadn't been much, but he'd helped where he could, when he could. It was the least he could do.
"Yeah," he said with a shrug. "Plus, to everyone there we have 'very cute accents' - " he said that putting on his best New York falsetto, then snorted and shook his head. "It was time to come home though. And I'll take you up on it, no argument. It's either that or move back in my mum, and we both know I'd rather starve..." Not that he didn't love his family, but he was a grown man.
He should probably tell Seamus why though, just to get it out of the way. And his face fell a little as he said, "Mum's sick."