It should be noted that Spock was not rejuvenated by the wavefront of the Genesis effect itself, but by the aftereffects several hours or days after the Genesis Planet had been established. Presumably, then, the wavefront would not have rejuvenated people aboard the Enterprise... Unless "aftereffects" and "off-focus effects" are more or less the same thing.
Not cannon, but there's a great Myriad Universe
story called The Chimes at Midnight
set in a reality where Spock died at the age of seven, and Kirk's first-officer is an Andorian named Thelin, who appears in TAS. Thelin manages to deflect the Genesis wave away from the Enterprise to save the ship at the end of TWOK.
Later, several crew members are found to have been affected by the wave and develop altered appendages in place of arms and legs. I don't remember the exact theory as to why this happened but remember being creeped out by it.