I think he was working as a criminal business transaction with ISIS. laundering money.
I would suggest ISIS didn't like him because he wasn't a practicing Muslim. Likely said the Shahada for them to accept him for the business transaction. Because of that he was going to die unless he proven himself a "true believer Allah"
Qur'an 9:111 generally says, all sins you have done in the past are wiped clean if you die fighting in the cause of Allah.
If he survived this attack he would go on laundering money for ISIS. If he didn't his family would live. I think his intention was to live. Either way it was his only way form himself and his family to survive.
Did you know that the Four Seasons hotel occupies the upper floors of the Mandalay Bay?
Ano that a Saudi prince has a significant ownership interest in that particular Four Seasons?