There are some routes in government (that don't involve crapita or their ilk) for getting access to good people where there's a need to pay more than standard civil service rates. If you want to bring top-level talent in house, rather than rely on expensive day-rate contractors, rigid pay-scale models start to get in the way very quickly, and hinder the ability to do anything.

It would definitely seem reasonable to shield a high-tech risk-taking organisation from overtly political attacks that ultimately jeapordise its mission - even the need to accept and handle FOI requests, correctly applying an existing exemption, will introduce more friction on an R&D-heavy, tech first organisation. If the programme managers are expected to spend a day a week checking FOIs to ensure the exemption claimed is accurate and valid, this just detracts from the mission.

It's strange this is the aspect people hare focused most on - one easy way to avoid the issue would be to set it up within the MOD as a defence research facility (as DARPA was). Making it more civilian focused may give better outcomes, but you raise a good point that if this initiative is held back by inability to pay market rate (and performance bonuses), it may end up worse in the long run.