They tested “345 hot dogs and sausages,” and found 2% of them tested positive for human DNA. That's only 6–8 contaminated hot dogs. If 2/3 of those were vegetarian, that’s just 4 hot dogs. I wouldn't jump to any conclusions from such a tiny sample.
Also, if the human DNA was caused by sample contamination in the lab, it could just be that the contamination is more likely to be detected in a vegetarian sausage than in a meat one.
Soylent Green?
>2/3 of the human DNA samples were [in] vegetarian products. >10% of Vegetarian products contained meat.
Sounds to me like the meat hotdogs are the better ones.