Of the two topics here both are hamstrung. Grant has a hamstring strain and hasn't really been tested this season so this is just stupid speculation off a slow race with a kick. For all you know Grant would have just taken the whole thing out hard.
As for Nikki, they also very CLEARLY have a hamstring issue given the tape all over their leg. Saying they shouldn't have left Mike based off their racing at less than 100% at one meet is also stupid.