We don't know the driver's mind when he clipped OP. That he did stop after does not imply that his driving was negligent rather than deliberate.

If he was buzzing cyclists deliberately, and struck him accidentally, stopping would be logical. Didn't intend to hit him, just to scare him, so stop and play it out.

An undirected drift in my experience is a smooth motion, sometimes a motion smoothly accelerating to the side of the drift. I saw an initial motion over the fog line, what looked like a correction and then a series of minor corrections. To me that implies control, which implies deliberate steering. It's possible that I'm wrong - I didn't examine the video closely. I'd bet that if you did analyze it, frame by frame and noting how the wheels are aligned, and the apparent direction, you might get something definitive.