Don't rebook the flight. The change fee is less than the probable cost of a hotel room. What you or your father might do is look at hotels and have a possible hotel with a shuttle ready to book as soon as you hear that your friend missed his flight and was not booked on the later flight. (And if the flight is late, as is usual for Newark, he might miss the later flight anyway.)
Now, I'm 1K with UA. My flight to Newark was late, I got booked on a flight to Memphis that was delayed. By the time I got to the gate the door was closed. They rebooked me on the next day's flight and got a hotel, plus dinner and breakfast vouchers. I'm not sure if I got the hotel and vouchers because I'm 1K or if they would do that for anyone.
I'd suggest going on and checking bags. By the time your friend clears immigration, the bags should be on the carrousel. He'll move much faster without a bag. He can ease his way up to the front of the plane and then move through the concourse much, much faster.