Yes, exactly. That is precisely the tweet I had read before.
But again, I dont think there is anything unethical in that. I think it seems unethical because he/she used the word 'bribe', and said they asked for him to stop work. Think about it this way, he/she literally said:
"BTW guys, a fun story to pass the time until 1.7.5 drops. Team Xecuter wanted to bribe one of the RetroNX developers into stopping work on their project and to make this OpenGL-enabled build of RetroArch 'exclusive' to their hardware. Unfortunately for them, m4xw sided with us!"
But if he would have worded it like this:
"BTW guys, a fun story to pass the time until 1.7.5 drops. Team Xecuter made an offer to one of RetroNX developers into going to work for them and to make this OpenGL-enabled build of RetroArch an exclusive feature for their hardware. Unfortunately for them, m4xw thought their offer wasn't attractive enough!"
Im pretty sure that m4xw is not under contract with libretro. This is what happens in business, you headhunt for the best people for your project. If your competitors are underpaying their employees, then you offer them something better and improve your project with their contributions. This is what keeps companies paying their employees GOOD wages when they are doing a good job in a competitive market. It keeps wages high, improves product quality, and offers employees with leverage against their employers. This is the reason why companies try to build loyalty in their employees, so they cant be head hunted with money alone. It forces companies to build up their profiles, and make attractive offers; in my view, it's good for everyone. Unfortunately for TX, they weren't able to provide an attractive enough offer for m4xw to switch sides.
Edit: Signing bonuses are almost entirely the same thing as a bribe, and yet they are a thing.