I agree to that, the deformation from heat will ultimately destroy its ability to be joined back together accurately. If for whatever reason they are structurally damaged from heat abuse, they'd be to deformed either way to put them back together, let alone take apart.
You probably already have a shop, but this is probably the most authorized race shop for nissan parts
https://www.nissanraceshop.com/produ...iper-rh-red-3/
If you are looking to just refresh the pistons/piston seals, you shouldn't have to take the caliper apart.
https://www.nissanraceshop.com/produ...0z-g37-rear-2/