I sure couldn't rule that out as a possibility. Since that sintered material that the pilot bushing is composed of has been oil treated, I would imagine that it getting between the contacting surface areas of the clutch would make it slip like crazy. And I would think that slipping would get worse over time as more and more material affected the clutch disk. Or maybe not. Perhaps the small quantities involved just got burned off by the heat of the friction, leaving the marks we see.
That being said, thinking out loud, I would imagine that material would have been slung all over the place and showing up in every nook and cranny in the clutch. Especially so in the splines of the input shaft of the torque tube and on the face of the flywheel where the bolt heads are located holding it to the crank. Which, as best I can tell, was not the case. Seems unlikely that it would ONLY get between the clutch disk and the contact surfaces of the pressure plate and flywheel.
Yeah, I know it would be logical to look for a common single cause of the two problems evident (1. crud around the pilot bushing, and 2. burn marks on the pressure plate and flywheel), but I am leaning towards thinking they are two separate issues. Actually I am surprised that the clutch disk doesn't show pronounced wear at the outside edge of the disk, since it is possible that it was contacting the pressure plate and flywheel at a slight angle if the pilot bushing wasn't holding the input shaft centered. But I don't see any obvious evidence of that. So I am thinking that the squealing noise was from the contact between the input shaft and the pilot bushing, and not the clutch itself. As many times as I have heard that noise, I would imagine that if the clutch were making the noise, there would be more evidence of it. Beyond the burn marks of course, which I would not think the low rpms at play when taking off from a dead stop normally, would cause. If I had been doing 6K rpm launches, well heck yeah, that might explain it.
I'm really leaning towards thinking that the Centerforce clutch just wasn't up to snuff for my car, and has been slipping all along. Of course, one of the test rides I took using EFIlive to monitor everything was specifically to look for a slipping clutch while under boost at high rpms, and I did not see any sign of them. The display line for car speed compared to engine rpm was pretty much linear. A slipping clutch would show up (IMHO) as engine speed suddenly increasing at a sharper angle than car speed (meaning wheel rotation against the pavement) as the flywheel and pressure plate started spinning at a higher rate than the clutch disk. But never having actually seen that in practice, I am just guessing.
Which I have had to do pretty much all along with this stuff.