I would imagine having poorer quality Cadets getting AD slots would do the opposite to the cutoff. In my mind it would make it higher, because a lot (most?) of these guys would be below the vanilla cutoff. So by filling slots from below the zone, there are less spaces for everyone else who may have scored higher but isn't in the ADSO-for-spot degree program.
I think that what this 2.75 ADSO program does is make it impossible for CC to establish the cutoff line before everyone has their branch/ADSO choices in. It used to be that you knew your OMS/OML position and the cutoff line before you had to commit your ADSO and branch choices. I think this is now muddy.
I suspect that the difference will be small in number as these are very narrow sets of majors and most below the cutoff line (without the program) probably do not qualify.
The bigger effect will be on those specific branches which will become a bit more competitive - especially in the lower 50%.