For the same reasons elected officials are not bound to electoral promises. There are procedures to remove people from offices and rules to limit their power, but elected officials should be able to act in their best judgment in those bounds, as in no "court" should be able to force a politician to pass/vote for a law.

It absolutely should apply for Trump.

But Trump already had a public history of crazy tweets (global warming is a Chinese hoax) and statements (grab them by the pussy) and he got elected anyway, so I guess the bar for sanity and impulse control is higher for a CEO in the eyes of the American public than for a President.

Or maybe not, since it doesn't seem like either has actually suffered any material, significant consequences for their actions.