That’s a bit beside the point in this case. Newspapers are supposed to have a first amendment right to say whatever they want and the key concern is that Bezos spiked the editorial to curry favor with Trump.
The first amendment issue is that he is doing it because of fear that the government will retaliate against his other companies.
A lot of folks are exhorting him to resist in order to protect the norm, but it his true that _his_ choice is caused by first amendment violations, not causing them.
I think you have the directionality backwards. Trump is not currently in office or in control of the government, therefore he doesn't have the ability to constrain Bezos' first amendment free speech rights.
If Bezos chose to constrain his own speech due to some perceived threat to his companies from a possible Trump administration, that's still a private decision (and an exercise of his first amendment right to non-expresssion).
To be a first amendment violation, the government has to constrain speech (via force or threat).