Not Voting = a Vote for X

Many liberals complain that if you didn't vote for any presidential candidate in 2016, then you voted for Donald Trump.

This is the same logic used in the False Dilemma. "If not X, then Y". By this token, "if not Y, then X" (which is why false dilemmas fail, because they can be engineered to produce the converse result).

There might be a political reason though; if it is assumed that Pubs turn out more than Dems, then Dems are already at a disadvantage in numbers and thus every vote means even more.

Of course, when assigning moral culpability, it is not helpful, since voting for a candidate carries connotations of approval (or at least, minimum loathing), so accusing someone of having voted for Trump, when they abstained, in order to tar them, is counterproductive.

There is some reason to this madness. Due to the two-party system, democrats who abstain from voting do help the republicans and vice-versa. It is the independent swing voters whose lack of voting does not help either party because their vote never "belonged" to ether party. This is what voter suppression is about... prevent the right demographic from voting and it can have a measurable impact on the election.

At least that is how I see it. Open to other interpretations.