We had that debate many time on Wotmania, and every time I had to track down the quote (from a signing, post WH, and no collected in the interview database), and every time it's useless because once they see it people start splitting hair over the issue of whether RJ meant it's made of the TP or it is raw True Power.

That doesn't really matter. I'm not sure what people who disagree the Taint is either the TP or made of it think it's made of. Whipped Cream Cheese?

RJ has also answered this by implication, notably when he explained the Cleansing. In the longer quote, he said the evil of the DO cannot co-exist with the Taint of Shadar Logoth.

I'm guessing Brandon see them as different because the taint wasn't a source of TP for anyone, that you could draw from like you draw Shai'tan himself.

That's like the solved issue in TGS (by LTT, confirmed as right later by Brandon) that Shai'tan is the True Power. That's another RJ had solved years ago by implication - quite a few times he has used the wording "draw on Shai'tan/the DO" instead of draw from Shai'tan.