By existing as a citizen in and paying taxes to the imperial core, we automatically hold complicity in imperialist oppression because we are literally footing the bill for it. That is just the basic nature of being born to privilege in systems of oppression in general. We can be disadvantaged and marginalized in every single other consideration and we still have to understand and cope with this, and ensure we leverage it as effectively as possible.
Voting abstinence/sabotage does not absolve us of our responsibility to do everything in our power to lessen harm, but it DOES show that when our personal morals aren't satisfied, we retreat into (imperialist, this time) privilege to 'wash our hands' of the situation and declare it's not our fault and it's not our problem.