Thanks for correcting this misconception. I expect that Stanford, like MIT (where I was), has policies in place explicitly prohibiting graduate students to work

Thanks for correcting this misconception. I expect that Stanford, like MIT (where I was), has policies in place explicitly prohibiting graduate students to work in any way for companies owned by their advisers or supervisors while working for them as students. It was annoying while I was in grad school, but it makes a ton of sense for preventing the appearance that a faculty member might abuse their authority to get a student to work on something that provides them with financial incentives. This is standard conflict-of-interest mitigation stuff, I'd be amazed if Stanford didn't have it in place as well. I think at MIT they can't even offer you a job until you're no longer enrolled to prevent sub-par graduate research getting through because an adviser wants a student to work for them. (i.e. "If you accept this job, I'll sign off on your thesis.")