The digital release system is just a new way to administer the pre-existing policies. None of the policies themselves have really changed.
If you were to CT from the RegF to the PRes, you'd still be "releasing" from RegF service, even if not releasing from the CAF altogether. It's the same as when members release and transfer (CT) to the Supplementary Reserve, technically the member hasn't fully released from service.
If a member is serving obligatory service or a restricted release period, they would still be unable to transfer out of the RegF.
Moreover, while there is a concept of "release as of right" (there's restrictions on this right), there is no right to a component transfer.