What's the legal theory that allows HashiCorp to control the use of data after downloading it? Is it like if I offered MP4 files on my website that can be downloaded by anyone but added the condition you must view them in VLC only? (which I'm fairly sure would be unenforcible even if the MP4 files were proprietary content)
The bigger thing, though, is that they don't necessarily need to be on completely solid legal ground. Just enough semi-plausible legal ground to out-spend you on the matter.
I think the freedom to contract is the main legal theory.
That, as long as there’s a proper contract that doesn’t contain unconscionable or otherwise illegal terms, then adults can enter into contracts with the consent of all parties, and the parties get to decide the terms of the agreement.