This doesn't excuse the war in Gaza, but similarly the war in Gaza doesn't excuse an act like this, if that was even the cause (we'll see as more info is released). If it was though, it's easy to say that each bad thing is bad and doesn't excuse the other bad thing.
All throughout history, you see the oppressed become the oppressor. People becoming what they fought against. When he was younger, Xi Ping criticized the government's actions during the 1989 Tiananmen Square "incident." Now look at him.