I don't have conviction on this other than to say I always thought it awkward that a business class passenger could use the business lounge and not the SEN lounge, but that a Star Gold passenger could use the SEN lounge.

It's like the airline treats elites of other airlines better* than people who simply paid more money to the airline.

*The SEN lounge is only marginally better, if at all, hang the business lounge, but you get my point.