It should not be that easy, for an attacker with physical access, to retrieve Tails memory. (Note that this will especially be the case for a Tails server instance left unattended.
other implementation ideas
- If a firewire card was inserted into the slot and the bus is active, pop up a dialog and ask "hey, you want to use firewire/etc.?"
- disable these buses by default, allow opt-in through tails-greeter to enable
- ask that users assert they want to use this or that bus, and make the assertion bind to a single device, rather than all devices blindly
- de-activate PCMCIA and ExpressCard on systems that don't have any PCMCIA or ExpressCard devices after running for 5 minutes. This is going to byte some users, but probably only the first time.