Ignoring the fact that, again, the astronauts in question weren’t in space for any appreciably longer time than anyone else on the ISS.
They’ll be too old to participate in the mars mission a minimum of a decade from now.
You have literally no idea what the radiation exposure allowances will be for a manned mission to mars when it happens, or what advancements we’ll make to radiation shielding should we ever actually send a manned mission to mars.
> You have literally no idea what the radiation exposure allowances will be for a manned mission to mars when it happens
These are well known and documented, to the degree we know things about human deep spaceflight.
> what advancements we’ll make to radiation shielding should we ever actually send a manned mission to mars
These are unknown. But they will, barring new technology, require mass. Which means more shielding comes at a cost. Which incentivises low-rad experienced astronauts.
They’ll be too old to participate in the mars mission a minimum of a decade from now.
You have literally no idea what the radiation exposure allowances will be for a manned mission to mars when it happens, or what advancements we’ll make to radiation shielding should we ever actually send a manned mission to mars.