The massacres at Sabra and Shatila were bloody, unnecessary revenge-lust bloodbaths, and tragic therefore.
They were not military operations, just massacres. Black September was the military response of a legitimate government fighting for its very existence against armed intruders.
The PLO and a plethora of other, even more radical armed Palestinian groups repeatedly tried to assassinate King Hussein and take over Jordan entirely with open, armed rebellion and defiance. They had the armed intervention of Syria to help them, even.
What the hell was Hussein and his Hashemite tribe supposed to do, lay down and die and lose their country? They attacked back, and civilians did indeed die in the mostly urban, do or fucking die fighting. The Jordanians put the Palestinian toll at around 1,000 - 3,000 dead, iirc, which includes all fighters as well as civilians.
It was the PLO and others who claimed, without any proof, that 10,000 had died. The OP now tries to inflate even that bullshit number to "tens of thousands" and to imply that it was entirely a massacre of innocent civilians.
So, in Black September a legitimate ruling government fighting for its very existence incurred unavoidable civilian casualties vs. the ugly, bloody, wholesale revenge massacre of a non-resisting civilians in a walled-off refugee camps of Sabra and Shatila?
And you, OP, wish to equate the two and then draw the conclusion that from news coverage that our press is therefore biased against . . . Israel?