Are you talking about Truman? One guy who started to seek the presidency, after serving 1.5 terms, and then pulling out before being the presumptive nominee? I don’t think history is on your side for this one.
Also, answer the questions please.
Edit: You actually said “We have absolutely aborted the campaigns of incumbent presidents before.” Implying that the candidate did not win their nomination. Let’s go ahead and put those goalposts back where they were initially.
Alright, so your position is invalid. Before moving on, please answer my original questions.