No he does not suggest that. That is your suggestion, if speaking of repair of radiation damage to a cell by cosmic ray passing thru it. He speaks of slowing the already slow (takes years) processes of aging. The killing of cells* by high energy cosmic rays occurs in a few microseconds, which in case you don't know is much less time than a year.
* Filling them with many oxidizing free radicals, and some broken DNA strands, etc. As with humans, exactly when the cell dies is a question of definitions, but their death is made certain in small fraction of a second.There are protons from space just drifting thru the solar system and others streaming outward from the sun. The faster you go thru this charged particle "cloud," the greater radiation damage it does to you each hour. I. e. there is an optimum transit speed and it varies with solar activity. I don't know what it is. Perhaps a faster transit would reduce the radiation damage, but you can not just assume that is the case. - Give some support for that / your view.
BTW one can be sure that the shorter the path is, the better. This means that either your stay briefly on Mars or several months longer than year. (In one year, Mars will have moved further along its orbit and Earth must too if you want to reproduce the shortest path for the return.) Although it is now technically possible to have a few people visit Mars, briefly, mankind is a long way from being able to feed them for say 16 months on Mars and protect them from cosmic ray deaths (with say 2x7 in two way transit + 16 on Mars) with 30 months of Cosmic ray exposure. I'm just guessing, but bet people eat several times their weight in food every 30 months. So staying on Mars for one of its orbits (687 days) is for the very distant future, if even possible.