Me too, their crimes against humanity are actually very high.
but we can't just drag them out because the conditions still favor them. Japanese military generals who commited massacre accross Asia are also not yet prosecuted until now because the U.S, as the winner, decided to not to prosecute them for some reasons.
In that film, there's also a guy that says that because he's a winner, he decides what law is. The bigger picture of his statement is, Indonesia today is a product of the war these "killers" had won in 1960's. They literally wiped out communists and they literally claimed the throne. So like I said, conditions still favor them because Indonesia today is what they had created.
Anyway, they didn't actually say they don't feel guilty to kill "chinese", they said that they don't feel guilty for killing communists.
I am not actually into this discussion, because it may open an old wound without finding any answer we both seek. But you should understand that their hatred towards Communists, who appeared to be mostly chinese, were quite justified because at that time, the PKI had also done many opressions to the common people. For example, land distributions, who forced the farmers to give their lands up and to be given a certain amount of lands according to the communist's rconomic system. Spreading propaganda against religion through LEKRA, etc. And Ex-Chinese communists in Indonesia were actually quite lucky compared to other communists from other ethnics, at least there were not many chinese got branded as communists forever by Soeharto and were allowed to prospere.
What I am trying to explain to you is: You, being a chinese born Indonesian, should not open an old wound, neither do I. At that time everything was chaos and those old men you saw on the film are the products of that chaos, let them hate what they want to hate, their lifespan is not that long, give or take 4 years and they will be gone forever. You and I are the products of the new generation, which has nothing to do with the chaos that happened in 1960's, so why don't we stop trying to expose wounds we don't even have?