"Regarding both the above quotes. Jim himself has already accepted his meaning was unclear.
Re-writing the sentence slightly:
"Some settled people are thieves and spreaders of rubbish, as are travellers."
Would you have accepted that I was not trying to tar all travellers with the same brush?"

Had I read that sentence, I would have perceived an implied 'some' immediately preceding 'travellers'. So yes, I would have accepted that you were not trying to tar all Travellers with the same brush.

Taking individual sentences absolutely literally is a fool's errand. Intelligent reading, taking a poorly-worded sentence within the context of a larger piece, can often clarify the true meaning of such a sentence. It was perfectly clear that, within the context of his whole piece, Jim was trying to demonstrate equivalence within the two groups under discussion, and not attempting to prove any superiority of either with regard to theft, dumping, etc.