Docr. Franklin was for retaining the clause as favorable to the executive. History furnishes one example only of a first Magistrate being formally brought to public Justice. Every body cried out agst this as unconstitutional. What was the practice before this in cases where the chief Magistrate rendered himself obnoxious? Why recourse was had to assassination in wch. he was not only deprived of his life but of the opportunity of vindicating his character. It wd. be the best way therefore to provide in the Constitution for the regular punishment of the Executive when his misconduct should deserve it, and for his honorable acquittal when he should be unjustly accused.

-The records of the Federal convention of 1787, volume 2, p. 65

There is nothing about him thinking “the alternative too terrible to contemplate”. He merely thought it would deny the executive a chance of redemption - Does anyone think Trump could redeem himself in his last few years of old age when he never has prior?

To think a man who only a few years prior had been a key political figure in fighting a revolutionary war, something that famously leads to bloodshed, would be abhorred by the concept and become a staunch pacifist is a bit silly. Not to mention the whole aforementioned quote you won’t share and which I’m not going to repeat here for that reason.

Also Franklin was not the sole reason, they all debated on this topic.