For instance, I've read (I think it was in "Fast food nation") that factory farms in the US are often staffed by people who are not legally permitted to work or reside in the US and who are at constant risk. They generally don't have much education or options, and have no recourse if they are mistreated on the job or denied pay. I'd also be disinclined to hold a burger flipper at macky d's responsible for, well, macky d's.
A patent troll, on the other hand, is a well educated person, almost certainly a US citizen or someone with legal rights and options, who had every opportunity to choose a different path in life, and indeed still does.
By the way, there's this job where you collect vast amounts of personal information about people, who may be unaware or only semi-aware of what is being collected, and then using sophisticated machine learning to get them to click on ads... where does that fall in the spectrum of harmful jobs?