Actually we did clearly mention it: "Our colocation providers could be compelled to give physical access to our servers." But in the very next paragraph:

Actually we did clearly mention it: "Our colocation providers could be compelled to give physical access to our servers." But in the very next paragraph: "These are not things we can protect against directly but again, we can make it extremely difficult for these things to occur by using strong encryption and careful systems monitoring. Were anything like this ever to happen we would be talking about it very publically. Such an action would not remain secret for long." Its not hard for a skilled sysadmin to take an image of a running server. Its extremely difficult to do it without administrative access to the machine AND to do it without anyone noticing.