But I don't think it is morally wrong to abstain from voting, especially if you figure on the evidence that the chance of stopping Clinton by your vote is zero, but the chance of being personally corrupted by the vote is greater-than-zero. I know my vote is not going to swing the results at my polling place, North Side School; nor will it swing Washington County nor the State of Tennessee. This for a virtual certainty. It won't change the outcome. But it could change me by being another augmentation of my cynicism, callousness, and willingness to accept the mainstreaming of sleaze and re-norm my own life around the putrid cultural zeitgeist.
My own prudential judgment moves me to vote for Trump anyway. But if I thought it was corrupting to me I would not. I don't think abstaining from voting is a mortal sin if it is avoiding a near occasion of sin.
To quote you back at yourself, with modification,
"Voting for Trump as if it were morally obligation is like going into the voting booth, voting, and masturbating while yelling, “Salvation through sleaze! I am saving my soul! Everybody else is going to hell!"