Its pretty simple really. The stop ride notice is corporate CYA liability protection. Somebody somewhere (probably in communist California) spilled gas all over their machine while fueling it up. Then, without letting it dry first, they hit the ignition switch sparking a fire. A multi-million-dollar lawsuit was filed blaming the owner's stupidity on Polaris. Polaris, at the direction of their legal department, then issued a stop ride/stop sale order so that when the next dumbazz does the same thing the company is protected. Owners of those machines have now been warned of the hazard of doing such an idiotic thing and can't blame Polaris if they ignore the warning.
Same reason your new ATV or new step ladder have idiot stickers plastered all over them telling you not to do stupid stuff. And this is why those items cost about 50% to 75% more than they should. Tide pods have a warning not to eat them and car batteries remind you not to drink the contents, etc. etc. and on and on...