You aren't going to get very far at all into the terminal, and certainly not where you can meet him. I don't see why he couldn't leave and then come back in though while passing through security. If his final departure is in the US, he'll be clearing customs here anyway.

There isn't much for restaurants directly around IAH, but I would feel totally comfortable picking someone up from the airport, driving to Pappasitos in Humble at 59 @ 1960 and getting them back in plenty of time. That's probably the only restaurant anywhere near there I would take somebody to.

When is the flight?