Not trolling, and not blind. The first elbow on the turn seemed perfectly in keeping with normal bumping, but the second one appears to be an outright shove. If you pause or frame-by-frame it, you can clearly see Engels' right arm essentially fully extended, and you see Kessler take an awkward stumble because of the shove. It was not a hard elbow, but an outright shove.
Several people feel that this is a normal part of racing. Others think it's a little over the line (but not DQ-worthy). That's why it was pointed out, and that's why we're discussing it.