The question still stands, what an earth does it that have to do with bmi?

Your question is about SAS and about Virgin...
A codeshare flight operated by SAS but with a bmi flight number is still a SAS flight.
The page you mention links to another one:
http://www.virgin-atlantic.com/en/gb...&bfSubmit1.x=8
where it says
The Mileage credit is not available on flights offered by SAS but operated by another airline.
and this would indicate the reverse is also true.
You're complain is not with bmi, it's with SAS or/and Virgin.