He came there to kill Nancy because the Republican Party has been vilifying her, calling her evil and/or crazy, for 19 years, and is now at the point where average citizens who express a lot of anger and hate online take their cues from shameless rightwing talking heads and go attempt physical violence against people like Pelosi, because they see themselves as following orders and only they can carry it out. That’s what happened there, nothing more or less, and anything else you’ve heard is not backed by any evidence, and comes from non-credible sources, as the Republicans try to both-sides the situation, as they always do.
While funny in emoji form, it’s overall a poor-taste joke, like putting up a picture of a sheet and a noose.