This is certainly not the first time I've heard of Amazon being a shitty place to work at, and I don't see much reason to doubt the story of a vindictive boss doing everything they can to make an employee miserable after learning that the employee submitted bad feedback against them.
The two lessons I can extract from this post for myself are.
1. Never submit negative feedback via "anonymous" or "confidential" feedback processes at work, especially against a particular person, especially your boss.
It's been covered on HN before how these things are never really anonymous and confidential, and it should be kind of obvious to figure out if you think about it.
2. If you are at your job as part of your Visa process, you are essentially a slave with a slave's rights to match, and you are better off not rocking the boat if you want to complete the process.