Also note that in their current data, they list a max. load for RL22 and the 100 gr. TSX at 69 grains.
Myself, and I suspect many others who shoot the .257 Wby, have been loading 72 gr. for years, with success.
The old Weatherby Guides, last published in 1985 was (is) a great source of load data, as they always cited pressure and factory equivalent loads using Norma MRP which is the twin of RL-22. The data there lists 71.3 grains of MRP for a factory equivalent load for the 100grain load and it's spot on on all three of my 257 Weatherbys, two MKVx and one Howa. I've also been able to duplicate the 300, 340 & 7mm Weatherby almost to a tee with the factory loads.
