Friend of Max.
The cams didn’t seize. The crank seized on the con rods. Turns out lubrication is kind of important.I'm not making the connection between the t sprocket and the valve timing. The bolt can't completely fall out until the cover is off, so it couldn't have jammed into the cam drive. The cams would not seize in the bores with reduced oil pressure either. For me, I'm still leaning on a major component failure, like rod or balancer in the case of the OP thread.