SpaceX is accused of illegally firing employees who wrote a letter criticizing Elon Musk

• SpaceX fired employees for criticizing Elon Musk, a US labor board complaint said.
• Rocket firm's workers wrote an open letter slamming Musk's "inappropriate" posts as a "distraction."
• It's the latest of his companies to be accused of unfairly dismissing staff for criticizing Musk.

Elon Musk is facing yet another headache over his controversial posts on Twitter, now X.