Everything that Trump does has to benefit HIM.........one way or another. The assassination served him too. Distracted the media from the Impeachment.........and placed the attention back on him.........where he could act like a dictator terrorist.........threatening cultural icons. ....just as the Nazis did, the terrorists do. No SANE leader behaves this way.Of course he didn't need to but since when has that stopped Trump from ever going after any opponent, worthy or not. Trump rarely does things because he needs to, he does them to be the center of attention and make himself look superior. Whether Biden would be the candidate or not Trump saw him in the lead and acted accordingly. And remember, many Republicans didn't want Trumo as a candidate either, and look where we are now.
Each action from Trump is getting more aggressive and more autocratic in style. The legality of this assassination is highly questionable......but his gang of lawyers will spin it to make it legally acceptable. His enablers will support him with a loyalty and devotion not seen since Hitler......... or terror groups...........Meanwhile the nation is morphing into an unknown entity. with characteristics of an autocracy.