Probably not much help, but personally I wouldn’t trust an offer like that, despite what they say, buying an account that’s linked with a 5 year subscription, doesn’t seem legitimate and it just sounds risky. I agree the reference to a business license part of an academic licence didn’t make much sense to me and who knows what caveats it may come with.
Office 365 support agents, which in the majority of the cases are working for a vendor and not Microsoft directly, are definitely not the authority on licensing. Neither are any of us posting on these boards. Your local Microsoft representatives are, so contact them directly and clarify this with them.
That's assuming he wants to be able to defend his purchase against a potential audit, technically the products will work just fine otherwise :)