As i thought, So6p does not have red hair..
So in the latest "next week on naruto" part of the episode, we got to see so6p's hair colour.
as you can see in the unshaded part, it is gray, just like hiruzen's colour actually.
It is gray, not white.. red hair turns white when aged.
This could not have been possible in any case because the red hair we see from the uzumaki's was taken over by nagato even though his father had black hair so if So6p would have had red hair, we would have seen more red hair from his descendants, the senju and uchiha.
Now you might state that they were created by creation of all things jutsu but Derp Obito himself claims that this is not the case in a discussion we once had..
I'll update this part when i have found the arguement he brought up.
now this does not mean that the so6p was not an uzumaki, this might just mean that the so6p did not have the red hair gen, wich means that they did not start the red hair trend back then^.^