If he was a homosexual, then cruising the bar to blend in and get intel for an attack was an excuse to do it - and then killing them was necessary as his only way to get into heaven.
Kind of like the Muslim men who rape girls, then tell them they have to be suicide bombers because only virgins, martyrs and well behaved married women can get into heaven, and martyr is the only option left to them. The rapists’ excuse is that the girls make better suicide bombers, so it is justified.
The immorality then becomes acceptable because it is furtherance of the goal - scare as many as possible into converting to Islam.
Day of the Jackel