I can confirm that the offer & site are legit. They are official Microsoft Academic software resellers click here.
One is ineligible to use unless: "...the end user licensee must be a student or be a faculty member in one of our listed educational institutions." - more in the FAQs click here
As I understand it, the end user licensee - in this case your cousin - will not be using it at all.
Also see click here.
Regarding its use for business, that would be a no too unfortunately. G