This is a prime example of the "crunchy outside, soft inside" response to computer security. The entire system fails following the subversion of one machine on the inside. If you use a "soft inside" platform that subversion can be done by something as trivial as reading an e-mail. Securing the traffic of a subverted machine is of no benefit -- it is just as useless as a website with a "128bit SSL" logo writing credit card details to disk on a compromised machine.