Alexander,
If this is supposely to be a potiental hit of a underboss, I don't believe that Al Neri would have sleepishly asked Micheal if he wants Frankie to leave now with his head down on the bar. I just think you are making waaay too much of the line. To kill someone because they insult you is childish. I don't think kill someone for leaving the room without permission. Hence, I don't think Al Neri to dare ask Michael if he wants his underboss killed because he ended the meeting and not Michael.
We can always agree to disagree, Alexander