The problem isn't that people are demanding accurate dates for launches and then getting mad he wasn't exactly correct, the problem is that he is underestimating launch times significantly and stating them publicly with confidence.
But these are actual dates he gives his engineers. Unsurprisingly, engineering is very difficult. He's pushing them to reach the stars, and they've only managed to reach the moon so to speak. He's fanatical about pushing them to be their very best (depending on your POV).