Immigration status and IRS status are two separate animals.
The above that RLCarey is explaining is what I think is confusing you...
His immigration status is not defined by his tax (IRS) status.
In your case you have an NRA that has been approved by DHS - Department of Homeland Security - to work in the US and therefore IRS has given him an SSN reporting number.
But you are back to ... if you are opening a Non Interest Bearing checking account, you do not need to complete a W8 BEN.