Why is it perverse?
The Palestinians are at war with Israel and seek the destruction of the State and the slaughter of the Jews who live there.
So, like any normal people, they hope for victory in their war, and they celebrate things which bring it closer.
What is perverse is failing to celebrate in the streets of Israel when IDF jets bomb Gaza, or when IDF soldiers attack Hezbollah in Lebanon.
That's not only perverse, it's suicidal.
Some folks would argue that any country that actually celebrates death and destruction probably wouldn't win many wars.