The characterisation of state educated applicants and students as disadvantaged bears no correspondence to reality. The top 1% of earners is more or less evenly divided between those who use the private sector and those who use the state sector to educate their children. Conversely, most families that used the private sector when the university set in motion its "participation" plan were not even from the top socioeconomic quintile.
Cambridge decided because of interest in this matter from "public, politicians and the media" to discriminate against applicants from private schools. This had nothing to do with widening access or giving bright disadvantaged children another chance, which was separately targeted. They were even happy for their exam results to take a hit as a consequence. Parks, who was the outgoing director of admissions predicted this would happen, and had he not, it should have been obvious.
Educationalists put a lot of effort into showing that grammar schools "don't work", the reason they get better results than other (nominally unselective) state schools is selection. However, the same educationalists assert that the rules for academically selective independent schools are different, for these schools a vague school-level attribute falsely elevates the performance of their pupils - class sizes (only shown to matter at primary level), coaching, take your pick - even though there is solid evidence that like grammar schools their results are driven by selection. So if academic selection drives outcomes, there was only one way Cambridge's move to non-academic selection would end.
I don't see any possibility for confusion regarding who is discriminated against when it really matters.