1) No, that's isn't at all what they claim. You think they said A, whereas their words actually say B.1) According to Hodgdon, LVR powder is used in Hornady .338MX and .35 Remington factory ammunition.
2) No reason it would be inappropriate to try it in the OP’s rifle - if he has the skill to safely develop a load.
Unless someone has some load data for that powder in that application, no amount of "skill" will inform them of the pressures being run, and therefore the safety of the load. Only equipment and testing can inform you of such things.The list of cartridges and bullets is limited with this highly specialized powder, but where it works, it really works!