I don't think you can deploy like ricin like that
and nuke stations (again AFAIK) are already built sturdy enough to withstand something like that which is probably why they didn't do something similar first time round.
( Fenris temporary Lazarus, Thu 7 Jul 2005, 13:29, archived)

Can't you just dust a little ricin around the place?
Or do you have to spray it somehow?
( Mr. Tea 'ulmmm'/'mmneurgh', Thu 7 Jul 2005, 13:36, archived)

Just been reading up on it here
www.bt.cdc.gov/agent/ricin/facts.asp

Looks like you're right but I should imagine that without it being injected it would be about as effective as the Anthrax letters - ie not very
( Fenris temporary Lazarus, Thu 7 Jul 2005, 13:41, archived)