Regardless of whether or not Miso is right to evade their promise of a bonus, I'm not so quick to heap sympathy upon rremoncake.
You hire a plumber to do a major job. You're in a hurry. You tell the plumber, I'll pay you a bonus if you finish this by (date). The plumber accidentally floods a downstairs room in the process of doing the job, but he finishes the work by the date you asked for. The flooding costs you an amount equal to or greater than his bonus. Weeks after the job is over, he asks for the bonus.
How excited are you to give it to him?
Clearly Miso owes him the money. Clearly it would be right for them to just pay him and move on. But if I were rremoncake, I would have been so embarrassed by my screw-up that I wouldn't have ever even asked for it in the first place.