In all honesty, I wouldn't know for sure which seat maker supplied seats for these Hawthorne bikes. There's probably better than a 50-50 chance they were Troxel seats, however. I have a 1950 ladies Hawthorne with the original Troxel seat. The older bike ads used to many times state the make of seat used along with makes of other equipment, such as New Departure hubs and Torrington pedals, but I don't think they did that very often on 1960s and later ads. They mention features of the bike, like in your ad images, but don't specifically state makers of the equipment on the bike.
Dave