Keep in mind how bureaucratic it can be inside well-established journalistic outfits.
For one of the mainstream outfits with someone pushing to join Fediverse I can imagine a ton of meetings talking about everything from budget, through technical workflow, through reputational impacts with marketing, through even having it cleared with legal.
They have #Twitter figured out. This #Fediverse thing gets to be more complicated.
A site like #Newsmax simply has less to lose, and maybe fewer employees demanding consultation.