My thoughts are that its a different bonus and the T&C are different in that it says you cant be an "existing Starwood Preferred Guest (Business) Credit Cardmember"
If you're applying for a business card then you couldn't have had a business one before.
If you're applying for a personal card then you couldn't have had a personal one before.
It's the same credit card.
It's always possible for a churn to go thorugh, unlike 4 years ago though it's always a YMMV these days.