You're right it's not necessary if you're the buyer, although I suppose if it was hostile-ish you might need every dime for the war-chest.

Not necessary in a coordinated merger, although the two management teams would naturally hash out what they'd like to see from each other in the run up to the Big Announcement, and that could hypothetically be cash and/or cost savings.

Sold, yes they probably want cash on hand rather than stuff like new ipads. They definitely don't need brand loyalty in that case either, so no need at all to take care of the customers with schedule integrity.

However... union CBA's are an important line-item on the balance sheet, it's often preferred that those be settled before a deal is done just so the buyer knows what he's getting into and can do his merger math. Especially for pilot CBA's, which are a very large line item. I know deals are done with CBA's outstanding but it's usually not preferred. Although maybe they sense that in order to ink a CBA quickly they'd have to raise the bar higher than they'd really like to.