I'm in agreement with everything you said, but none of it applies.

The US (or any other country) should never intervene due to a "bad person" or "illegitimate" or "dictator"

Instead, US intervened because the policies of Maduro directly led to the flight of 8M causing harms to many countries in LATAM, and US.

If a dictator was not actively enforcing policies that made foreign innocent (bystanders!) neighbors hurt or destitute, then your argument would apply

It was not a war bullet that have killed random Chileans, or Ecuadoreans or Americans. But nevertheless, there have been hundreds of venezuelan bullets (and drugs) kiling everyday civilians. The act of aggression exists (exporting hardened criminals and economic destitutes abroad) .

That was the casus belli. The US just happened to respond in force, when other countries couldn't.