The comparison between ISIS and Hamas (a claim no intelligent or respectable historical, anthropologist or political scientist will likely ever make in the way described here) is an idiological comparison, not an intellectual one.
We already established Hamas is bad, no one disagrees. But a step further is needed to excuse the unspeakable and unrelenting massacring of Gazans and the destruction of their homes. It's to say, "LOOK! WE ARE FIGHTING (K)HAMAS-ISIS! THEY ARE LIKE ISIS!!!! REMEMBER ISIS????"
Edit: typo