I found one interview that references what I said. There is another one, where Pop specifically uses the word sponge to refer to Kawhi (while he was still in the team, I think Pop was trying to prop Kawhi up for MIP at the time and even for MVP), but this one still gets the same point across that I was making.
In addition, this interview is so interesting in the context of talking about draft picks because he says how when they get a guy drafted they don't really know what he's going to turn into. Anyways, for reference here it is. Enjoy.
FWIW, It doesn't tell us anything about whether Kai is going to pan out tbh. He might, if he is obsessive about his development and has the special ability to learn.