Was this guy selling cups of small spherical ice cream? Because it sounds like he was the dippin' dots guy.
12 months to paint Rivals if it were completely shut down to do the job? BULLSHIT.
Unless they're completely stripping it, a new coat or two as part of maintenance shouldn't take too long, provided the weather is kind. I won't put a number on it, but 12 months it isn't. Definitely less than 6. I think he might have been pulling your leg matey.
Local painters with these skills already exist. They paint buildings and bridges and all sorts of things. Roller Coaster Painters aren't a specialist industry (although its quite reasonable in a country with as many coasters as the USA that they might have a specialist company that only does coasters). There used to be a company that had website images from their work repainting Lethal Weapon back in the day, and to be honest I reckon Lethal would have been the harder one to work on - A skyreach EWP platform can reach 150ft, meaning most of the coaster can be reached by a suitably qualified painter without additional equipment. The drop is 200ft, so everything else is lower than that, and the drop can be accessed by qualified abseiling crews (my multistorey building was painted by crews like this), so there is very little that can't be reached with a single EWP and some ropes. (suitably qualified personnel obviously, and you'd be surprised how many of those exist locally). Anything you can't reach is gonna need a crane and a man-basket but they used that to build the damn thing so not difficult to get them in again.