Very few executives are more closely identified with their companies than Howard Schultz and Starbucks. The suggestion by Mr. Schultz that he is considering a run for president of the United States as an independent has a lot of people, particularly those who want to make sure that Donald Trump doesn’t get a second term in office, upset with the might-be candidate. Many of those are willing to express their displeasure, it seems, by taking their coffee drink business to places other than Starbucks.