I've been the manager of a meat processing plant for about 8 years.
The kind of machine Trip was rolled into (it looked identical to a mixer-grinder) has a counterweight and scale on the inside of the machine, well before any of the bladed mincing tools reach whatever's been guided in. This is generally used for doling out meat in specific measurements (if you haven't noticed mass-produced meat is extremely specific in it's weight for the sake of pricing) but, as a sort of unintentional bonus, can also prevent accidents like a live person rolling in. I haven't had it happen at my workplace, but I've spoken with people who hired badly, ended up with some pothead falling asleep on the belt and tripping the alarm. Most of these machines are also nowhere near large enough to fit a grown man. You don't chuck whole dead animals into a robot and get sausages.
Given Trip Larsen almost certainly weighs more than seventy-fifty pounds (the maximum weight these machines generally allow before activating a failsafe), the fact that mixer-grinders have had the mentioned weighing tools built in since the 1950's, and the lack of in-story mention of a man being rolled into a meat processor and killed (which, along with food being contaminated with a dead person, would have made national news and Arlington a brief celebrity) we can assume that Trip merely "tripped" the scale, the machine turned off and he was rescued by authorities. Given how attentive the show is to blue collar work and its employees nothing else would make sense.