You don't know what cancelling a vote is, do you?Yeah, not voting is a thing. "Cancelling" a vote isn't.
An "act against democracy"? Sounds like idealist drivel to me. The right to vote inherently includes the right to not vote. Just as the freedom of religion inherently includes the right to not be religious. The notion that someone who doesn't vote (or someone who votes for the other candidate) "cancels out" your vote is infantile, at best. The value of a individual vote is not based on who the vote is for or even whether or not it's cast, it's that the individual gets to makes that choice. Criticizing those who vote differently or who don't vote is more an "act against democracy" than anything else.