Auto-translated
I assume that the person who declared they would pay anyone who could solve the problem within an unrealistic timeframe (according to their own standards) has now received several solutions and found themselves in a trap of their own making:
1. The money needs to be paid – and the amount isn't that significant, and they would pay if they had promised, BUT...
2. Acknowledging that the solution is correct automatically means admitting their own WRONGDOING. And that's where the problem lies...
Therefore, there's no need to say that they "held back the money," etc. – the opponent's priority now (possibly) is different: to stir up emotions, provoke an insult, and then slam the door with a disdainful look – this is the most likely scenario...