I didn’t reference the McDonald study in my reply, but I too am not particularly persuaded by the conclusions.
“Many think it means they will not be tracked at all, including collection”
suggests to me a fundamental lack of literacy among the users surveyed about what data that browsers pass with HTTP requests.
we are making use of the header that we think is consistent with the expectation of users
based on what evidence?
I’ve seen a single reference cited in this thread pointing to a study that candidly declares in its abstract:
“Because Do Not Track is so new, as far as we know this is the first scholarship on this topic. This paper has been neither presented nor published. “ 
The ample and representative sample considered by the EFF is well captured at the beginning of this statement:
“Intuitively, users who we’ve talked to want Do Not Track to provide meaningful limits on collection and retention of data.”
Nobody is questioning the need to be transparent to our users about what data we’re collecting, how long this data is retained and what it’s being used for. But I see a thread full of handwaving statements about “what users really want”, in contrast to a pretty straightforward truth that nobody who participated in this thread would challenge:
which departs from the standard in a significant way.
I don’t see myself blessing a proposal that represents “a significant departure from the standard” and I’d love to see more substantial evidence on user expectations to justify this.