This isn't a criticism of the fact that the SWTOR Sith are human, but rather of how the SWTOR Sith being human was explained. The explanation that we're given is that the red alien genes were bred out. However, in TOTJ, and even the timeline of SWTOR's own website, it's the human genes that have been bred out. Therefore, SWTOR should have mentioned a massive human population joining the red alien population.

I also want to say that the Sith being red aliens is a KJAism. KJA also made the Mandalorians a species! TOTJ itself suggests that Veitch intended the original Sith tribe to be a group of humans, not a species.