It’s not what they said.
By not voting, you are complicit with whomever ends up on the White House, that could be someone you like (and obviously it is for probably a lot of people who didn’t vote) but assuming you were eligible and able, by not voting, the statement you effectively make is ‘I am ok with any option’
No, if you vote for Democrats, and they win, you are saying you voted for Democrats, this is simpler than you are making it.
Not voting (when eligible and able) just means you are apathetic to the outcome.
Saying ‘democrats bad’ isn’t some gotcha response to this concept. Voting for someone who goes against their constituent, is a bad person, or otherwise isn’t what you expected is not the same thing as not voting at all, nor is voting for someone with a slim chance of winning or voting for someone that the general population disagrees with. All of those are actions taken to have some stake in the process and they are conscious decisions to support a specific person or group.
When you don’t vote, you implicitly support the winner, because by definition, you chose not to support anyone else, that’s just how the concept of voluntary voting works, it has nothing to do with the politics at play.
I wasn’t saying you personally didn’t vote, I was speaking colloquially, using ‘you’ to refer to the subject of the discussion (a person who didn’t vote).