Although he didn't talk to Batman much, Ivan knew very well that this guy was a man of his word.
What was even more interesting was that as long as he preserved this situation, that tycoon could only watch and not make trouble for him.
This was too interesting.
Luke didn't know this, or he would've laughed out loud. Wasn't this the real version of "I like when you get angry when you see me, but can't do anything about it"?
Since Ivan was happy to be the hired help, Luke didn't mind his little ideas.
Especially now that the Chitauri could appear at any time, Ivan, a guy who didn't care even if he died, was useful because he wasn't afraid to fight.
This was the most valuable point.
Look at the Avengers.
Tony would go beat up terrorists in his free time, and had participated in several major events with Luke.
Black Widow and Hawkeye were professional agents, and had very stable fighting mentalities.