.454 Casull is not .500 S&W.
Aftermarket conversions are not done by Ruger.
You're mixing and matching dissimilar concepts.
Just because someone like Bowen will turn a new cylinder and chamber a new cartridge doesn't mean that Ruger will do it.
Ruger has already established, during the .480 Ruger thin cylinder wall "scandal" (and their waffling between 6-shot and 5-shot models), that that is the largest diameter cylinder they are willing to fit to a Redhawk or Super Redhawk. ...And it isn't big enough for .500 S&W. No matter how many times you squint, tilt your head, change the lighting, or make wishful statements on the internet, what Ruger says is the largest cylinder they will fit to a RH or SRH cannot contain .500 S&W. There isn't enough meat for a suitable cylinder wall.