There is simply no difference between the president exercising his first amendment rights and you exercising yours.
This is not actually true. When a John Q Citizen speaks they are speaking only for themselves,when a Head of State speaks, especially when they do so over what we are told is an
offical channel of communications, then that Head of State is not speaking for themselves, but rather they are speaking for the entire Country that they are the Head of State of.
This is what you, and Trump, and Pence, and a lot of their supporters don't seem to get, because Trump is President, when he speaks he's not speaking as Donald J. Trump US Citizen, but rather President Donald J. Trump, Leader and Representative for all the people in the USA. When he tweets, he does so in the voice of the USA, it's not him speaking, but his office, and via that, the Country itself.
So no, you are not at all right that "there is simply no difference between the president exercising his first amendment rights and you exercising yours." There is a major difference, because no one here or on an NFL field is speaking for an entire country every time they open their mouth, or angrily bash their keyboards, and this is the HUGE difference in why Presidents are supposed to act and speak Presidentially, because everything they do reflects on the country they are representing, 24/7 during their term.
And BTW, in calling for Tax change, Trump might have crossed the line from moronic actions to illegal ones.