I think he's choosing to go by a different definition -- namely where "theft" is when you're deprived of what's justly yours by whatever unethical means; not simply when the law proscribes it as such. Or in other word: based more on an intuitive sense of fairness (or "natural law"), rather than what's on the books.
Granted, it's a fuzzier definition, and you may not particularly like it. But I'm just saying, it's a different one.