Post-Soviet Lithuania is rather *ahem* nationalistic. Why would they want to confederate with nationalistic, and more powerful, Poland?
The United States tried to involve Canada in the American Revolution. TheThis is like asking, "The US tried to get Canada to join the American Revolution in 1775; they even pre-approved Canada as a state. WI Canada agreed to do that now?" except worse. Okay, so pretty bizarre things can happen (France and Germany being best buddies against Britain...), but that's just too weird.