You're talking like the current president of the USA came out of nowhere, and was not at all a public expression of dissatisfaction with the status quo.

The president doesn't need to accept dissent from his staff. Just hypothetically, if Obama's health secretary said that being transgender was largely a mental illness, or his head of domestic policy said that we need to close the southern border, does he need to tolerate that? Just to be very clear - those are completely hypothetical - I am not sure what actual "dissent" caused Trump to fire his various staff members, but it is unrelated.