The S&W Governor is only rated for up to 23,000psi whereas .454 Cassul operates at 65,000psi, so even if you had someone reem out the cylinder to chamber .454 Casull, it wouldn't be safe at all.
Heck, even .45LC +P loads which typically operate at around 25,000-26,500psi would be pushing it.
Taurus makes a version of the Judge which can handle .454 Casull known as the Raging Judge, but the thing is an absolute tank that weighs 61oz for the 3" barrel model and 73oz for the 6.5" barrel model. I honestly think that the reason why Smith & Wesson never offered an answer to the Raging Judge is simply because a Governor chambered in .460 S&W Magnum would be so massive and so heavy to accommodate a cylinder with a 3" chamber for .410 Bore Shotshells and would likely cost so much to produce a whole new frame specifically for it that it just wouldn't be worth it.
I had given some thought into purchasing a Taurus Raging Judge in the past, but ultimately passed on it in favor of a Mossberg 590 Shockwave, because frankly all I wanted was an extremely powerful compact firearm that could handle shotshells anyway, so the $300 Mossberg 590 Shockwave made a lot more sense than the $1000 Raging Judge, and 12 Gauge Brenneke Slugs hit a lot harder than .454 Casull.
