[Apocryphon]

What your ascribe to nobility might simply be prudence. The American republic was founded on the ideals and rhetoric of anti-tyranny. Washington may have simply chosen the course of wisdom of not getting overthrown, himself. Or assassinated by any of his various rivals, such as Horatio Gates and the officers of the Newburgh Conspiracy, which sought to remove him as leader of the Continental Army during the war itself.

Maybe choosing not to be a dictator was simply the safest course of action. Least path of resistance.

[WalterBright]

Look at his later stepping down as President setting a precedent for two terms, despite being a shoo-in for re-election.

It's not consistent with him being afraid of assassination.

[Apocryphon]

Washington passed away two years after his second term. Him not seeking a third is consistent with him being old and ailing.