Another theory is that he might have thought it would accelerate the right leaning movement by killing or wounding Trump. It is also possible he liked the movement but not Trump.
Theories 1 and 2 don’t make any sense. Trump has too much of an ego for 1 and 2 would be weird. If you aren’t going after Trump, anyone else would be easier to shoot when not next to Trump.
Definitely go vote early. Poll locations are pretty crazy for early voting so election day is going to be insane.