I'd hate to work at a company (as employee or management) with such bad labor relations that "we screwed up on scheduling" can't be resolved reasonably.
"If we offer your a bonus, you might not get paid the bonus" either means the management is horrible/dishonest or the union are assholes and bitter about being excluded from negotiations, or more likely, both.
The entire point of a union is to prohibit members from making deals that are individually better but worse for members as a whole. The union here is in principle correct for wanting to be able to keep pilots from selling "fix the scheduling" too cheaply back to the airline.
Stuff like this blows my mind from a european perspective, here in Belgium you certainly make individual deals that are better, here unions are to support you when you are in the weaker position of negotiation.
While I'm against most unions today (at least in the US, and especially in the public sector), I do think the German industrial unions (where they have works councils with management, etc.) are a pretty good counterexample.
"If we offer your a bonus, you might not get paid the bonus" either means the management is horrible/dishonest or the union are assholes and bitter about being excluded from negotiations, or more likely, both.