Perhaps management never really expected anybody to sign for COS08, except +50yo captains.
Perhaps management just wanted people to sign for SLS, and their strategy was to give people two bad options, so people would take the "less worse" of the two.
Guess how many won't take COS08, but will take SLS, and still think they didn't give away anything.
I'm sure if there wasn't any COS08-COS99 choice, a lot less pilots would take SLS.