My read of your argument: international law says don't intervene in foreign government, and by intervening we legitimize future violence.

I'm not sure this argument makes sense. Maduro stole an election to force his way to dictatorship, is widely blamed for running the country into mass poverty, and continues to hold onto power through threat of violence. The Venezuelan people don't have any recourse here.

Also, in your example of Ukraine you indicate that Russia frames the uprising as a "US coup", suggesting that the reality of whether there even was external involvement isn't so important.

Even so, if some nation tried to use this strike on Venezuela as further justification for violence wouldn't they be violating the same international law you cite anyway?

Obviously the US has a rough track record of replacing foreign governments (a much stronger argument against this kind of act IMO), but so far this mission has looked pretty ideal (rapid capture of Maduro, minimal casualties, US forces instead of funding some rebel group). There is opportunity for a good ending if we can steward a legitimate election for Venezuela, assist with restoration of key institutions (legal, police, oil), and we avoid any deals regarding oil that are viewed as unfair by the Venezuelans.