That is a shame. On bigger jobs I have a contract chipper who subs for me with an 1890 with a winch. It's a great tool, but there is a very real danger of the cable getting caught up. There's an interlock so you can't operate the winch while the feed rollers are turning, but how these accidents seem to happen is that you can set the winch to freewheel while the rollers are feeding. Most guys winch in, get the tree in the chute, then freewheel the winch so you can setup the next drag while the last tree is going through. If you're not careful, the cable gets snagged in the tree being chipped and goes through, then you're screwed. You need to be extremely vigilant about it, a cable or rope getting past the rollers and into the drum = sure disaster, possible death. We usually have an intermediate guy standing off to the side, keeping the cable free of whatever is being fed and acting as a redirect. Otherwise you're pulling cable out directly over what you're chipping, and it droops.
Couple months ago I posted up an accident that a buddy of mine had where a lowering rope got caught in the drum. 2 workers injured, one fairly badly... but it was pure luck that nobody was killed. One of the guys is still of work now. Ropes and cables need to be kept far from infeeds, if they get past the roller there is no going back.
Shaun