I used this link for research in helping a friend get to Cozumel CZM next weekend, in that we could not find a cheap fare to CZM at the time, but we could find one to Cancun CUN.
However, American and Continental - listed on that site - now say that they do not have the flights. Mexicana lists two flights:
11:00 am Depart Cancun (CUN)
Arrive Cozumel (CZM) 11:25 am Sat 24-Jan
8:05 pm Depart Cancun (CUN)
Arrive Cozumel (CZM) 8:30 pm Sat 24-Jan
Since he arrives at 1:25pm, he'd have a 6 hour wait before flying to CZM, if the flight didn't cancel? For a lot less money, he can do the bus, then the ferry, and be at the Cozumel ferry dock by 6pm.
But, I'll ask him to look around while he's waiting for his luggage to drop, and see if any planes do fly CUN CZM, on airlines his mother would approve of. {We're both grown men, but I know his saint of a mother, and I couldn't come back if anything happend to him. He's been on two trips with me, one time taking a mild DCS hit when we were new to Scuba and his weight belt fell off, and another time taking a sailing cruise within 200 miles of Huricanne Debby.}
don