I don't want to get into a semantics argument here, but:
"The proportion of nefarious types (relative to the total user-base) routinely using Tor is going to be significantly higher then the proportion of such who are not..."
He is claiming that nefarious usage is significantly higher than non-nefarious usage. That's the exact meaning of majority.
No, I think he meant "...who are not using Tor". He's saying that if 1% of normal internet traffic is nefarious, that he suspects that > 1% of Tor traffic is nefarious.
That is to say that your odds of finding a nefarious packet is greater on Tor than on the broader internet.
I don't think it's worded very clearly, but at the end of the day there's only one reasonable interpretation. He's saying that (numbers made up and not realistic) 10% of nefarious types use Tor, while 1% of regular folk use Tor. If nefarious folk make up 1% of the general population, they'll make up about 10% of Tor users, and thus focusing on Tor users will get you a larger proportion of the nefarious.
Assume 5% of Tor users are nefarious. Assume 1% of Internet at large users are nefarious. The proportion of nefarious Tor users is significantly (5x) higher. But it's not majority.
In the context of normal law enforcement that would be like searching my car only on the basis of driving down a street where drug deals are are done relatively more often than on other streets.
