I think the fraction you're looking for is 3/5ths and the Constitution didn't define who was a slave, it defines who can be counted for representation in a way that eliminates everyone but the enslaved who happened to be black. Wouldn't want to dirty their document defining slavery as it was an accepted norm so why bother.

Thomas is a "free person" so the 3/5ths crap doesn't really apply. It's his marriage he has to concern himself with (see Loving vs Virginia), but then it may be a long term plan to get rid of his wife.

@redbai Thanks for the corrections, sometimes I just get going.