He had a point there. So, entirely unsure of what he was supposed to say to that, Stephen remained awkwardly quiet, as he'd never been the sort of person who knew what to say to someone's grief other than the most obvious thing possible. And while it had happened just five months ago, in something Stephen hadn't really thought his friend could blind himself to (or had hoped he couldn't, though it would have been a great reason to never speak to him again and vindicate his theory that there was no one out there anymore worth talking to).
When Matthew had finished reciting off the answer to his question, Stephen nodded and lowered his wand. Genuinely, it wasn't that great a question, since Tosvig's Constant was technically public knowledge. But Stephen was overconfident enough to underestimate what the Death Eaters might send to get someone who really wasn't of much interest to them. In any case, he had enough confidence now that this was really Matthew. He smiled. "Well, it's good to see you again, Matthew," he said.