Should a person who makes rational and fact based (either sources, etc) arguments about their support of racism, sexism, transphobia, etc be banned?
No.
How do you reconcile differences that may be “derogotary” with pure differences. For example, if I say Blacks are dumber than whites because of their inherent brown structure and provide evidence, should I be banned?
No. I would differentiate by the appearance of legitimate arguments. I will give an example of an argument and non argument.
1. Asians can't drive, fuck Asians
That should be ban worthy
2. Asians disproportionately get into auto accidents (citation)
That should be permissible.
The first one is an insult, even without the "fuck Asians" part. The second one is an argument. I wouldn't limit this to just popular groups to white knight for. The following thing would also be banned
1. All pedophiles should be castrated.
While the next statement is acceptable
2. Castration of pedophiles will likely lead to less children being raped.
You see the difference? We want a free market place of ideals, and it should have a balance of being civil while also being allowed to be heated.
*do or do you not* believe that white supremacy should be advocated for/debated on the site when it includes evidence?
It should be advocated for if somebody believes that, and the person should be treated with respect and encouraged to stay, so they don't retreat into some echo chamber that results in a dangerous purity spiral.