If you state "I won't cooperate unless I am ordered to by a court." then you did not prompt them for subpoena. The door is also still open for them to explain why they won't get a court order in which case you might still reconsider.
Could you explain what exactly you see as the difference between "I won't cooperate unless you subpoena me" and "I would like to cooperate, but I don't want this to affect my future job prospects, so please subpoena me"?
The OP is prompting the subpoena in either case, as far as I can tell. In either case, the other side can choose whether or not to subpoena him/her. I'm not sure I see any difference between the two...
The first option could be legitimately said by someone who doesn't want to talk or be subpoenaed. It's the difference in occupy style protesters saying "They'll have to come arrest us." and "Please come arrest us.". Though in both scenarios there may be some that get the desired end result, the first option places the responsibility for the end result on the third party.