"Our guests' experience is a top priority at Firehouse Subs and we're saddened to say that this guest was not treated with the heartfelt service we expect at one of our restaurants," said Firehouse Subs.

“As [an] international student, this is a very sad experience in United States. And I don’t understand why people have this problem in USA?”

From his family name I assume he is from China. Given his country is completely xenophobic and "racist" against various groups of its own people, I might understand if he is shocked to find the our country has any racists. It is naive, but understandable.

Until I read this. “I do not accept the manager’s personal [apology],” Zhao wrote, adding that he believes the manager is responsible for any “racial discrimination” by the employees.

Now he has gone from naive foreigner to little more than an activist, and might actually be a Chinese plant.