This seems a odd stance to take. Whether or not Yahoo! is/was involved in PRISM seems divorced from their giving up of a Chinese political activist / radical. I

This seems a odd stance to take. Whether or not Yahoo! is/was involved in PRISM seems divorced from their giving up of a Chinese political activist / radical. It might mean that you believe them capable of participating, but we don't even have direct confirmation of what PRISM is exactly. What if PRISM is a worm sitting on Yahoo!'s network? What if PRISM is interception of network activity going to/from Yahoo! and sending it off to some NSA data-center?