> to reduce the effect on profits (but why? surely the company's profits are boosted by the deal more than the cost of the commission?).
This.
Either SAS fucked up their commission structure, or the whole "but what about our profits" thing is a bit of a red herring - the sale price presumably included enough margin to cover the commission rate.
It might have been legal, but it's also a damn good way to dissuade any (good) potential employees from bothering