Yep. The proper reply would be, "Thanks. But, I don't work for your company and am not bound by those rules. In fact, it's the policy of journalists to seek the truth regardless of your company policy."
I think their issue is that TaskRabbit contractors can't talk to journalists without going through corporate PR. (While nothing prohibits a journalist from asking, I'm sure the contractors would be terminated for speaking with journalists if corporate found out.)