President Trump has asked whether it is constitutional to bar CNN, MS NOW, and Politico from the White House. A Reason article takes up that question by pointing to D.C. Circuit precedent, noting that the D.C. Circuit is the federal appellate court with jurisdiction over D.C.
The article suggests that the legal answer depends on how courts treat White House press access under constitutional constraints, rather than on the President's own view of his authority. It does not treat the President's social post as the final word on the matter.
With only one source in view, there are no differing positions to compare. The analysis is framed as a legal question for the courts, and the article directs readers to D.C. Circuit case law as the relevant framework.