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.)
“Please know that it is our policy that all journalists work through TaskRabbit Corporate for these requests. We’d be happy to coordinate interviews.”