Tommy had a point; none of them really knew what exactly Billy had done. There could still be copies of themselves back home, living out their lives as normal. How awkward would that be? And they had to assume, even if the others did happen to end up here as well, that they might not have known as much as they did-- or they might have known more. "Even if they see Billy taking out the Hulk, they don't know if it's, you know, Billy, or some other Billy. Or maybe they found their own way back, thinking that, you know, they were the only ones here."
If that was so, Teddy's choice might have just been made a little easier. But he didn't know if there was any way to find out-- what, broadcast a message, 'Have you sent these people to another dimension?' He was pretty sure Directory Fury wouldn't like that too much.