Bingo. The only UAL 737s with a FAR 117-approved rest facility (Class 3) are certain 737-800s in the Guam operation. For those ships, 1AB were removed and 2AB was replaced with a barcalounger-style recliner with a foot/legrest. The standard 737 F seats do not recline far enough, nor do they have foot/legrests, so they cannot qualify as a Class 3 rest facility.

The 757s, of course, have flat beds, so the flight could be operated as a turn, but the added staffing costs (1 additional FO/IRO) and higher operating costs of the 757 make a one-stop 737 operation in AUA more favorable. It seems that UAL is simply trying to cut its losses in the CCS market while maintaining a presence due to the uncertainty of the political consequences of cutting the route entirely.

It CAN land heavy... in an emergency. Overweight landings require a maintenance check and can cause structural damage. It would never be a part of normal operations.