It also requires equating the ANC with the uMkhonto we Sizwe [0], making wrong claims about their targeting, and embezzling how the creation of the uMkhonto we Sizwe was a direct reaction to getting massacred when initially attempting peaceful, non-violent, protest [1].
Not to mention how the US's role in Cambodia is in not at all analogous with the role of the AMC in Apartheid Africa. Even attempting this comparison, to argue for some kind or ethical nihilism, is something very weird to do.
Wouldn't you agree these are generally "good" causes, unless you are the aggressor in that situation?
The inherent asymmetry of these conflicts, particularly in military power, leaves the "insurgent" side usually not much more choice than use cruder weapons and go for targets of opportunity that may involve a higher risk of civilian collateral.
Which is not a new dynamic, it's a very old dynamic that many militaries throughout history had to deal with when occupying populated territories hostile to them.
How it seems to work is if said person aligns with your own political views (i.e. the ends justifies the mean) then war crime are conveniently overlooked.