The true cost of downing tools
These engineers are not just people bolting seats to the floor. They are the boffins who sign off on complex design changes, troubleshoot the inevitable production snags, and cajole the necessary certification paperwork through the labyrinth of regulatory approvals. Losing them, even for a fortnight, would have been catastrophic. A picket line of highly skilled technical staff is the absolute last thing you want when you are desperately trying to convince the market that you can actually build aircraft safely and on schedule.
Avoiding a walkout is arguably worth a king's ransom to Boeing right now. The specific terms of the contract hardly matter compared to the terrifying cost of halted production.