It definitely wasn't the first time Ginny had told Harry to shut up, so he did. He knew that when he was making her mad, it was best to give her space, and try to not cause more tension in the house than necessary. He supposed it would be the same here, only the house is the baggage station.
In all honesty, Harry was used to weird things happening. It didn't matter what it was, Harry tended to roll with the punches, and think quickly on his feet. Surprisingly enough, while this situation was strange, he wasn't that concerned. Whatever happened would right itself eventually.
"I don't know, I mean, if they weren't born yet, which in 2004 they weren't born yet, so, if you're from 2004 then you wouldn't know them?" He confused even himself with his explanation. It still didn't answer HOW they were from two different times.