I think you should consider the Heritage Foundation's intentions in the context of the recent Supreme Court ruling greatly expanding the authority of the President in their capacity to carry out the "core powers" of their office without "fear" of legal repercussion. Putting as many federal departments under the oversight of DoD and the Department of Homeland Security presumably means you have much stronger legal case that xyz decision relates to a "core power" of the presidency and is thus legally immune to potential investigation let alone any legal accountability.