He is that / so kind a person, and everyone likes him.
【参考解析】用 so / that 都是正确的。刘老师的讲法不符合英语的实际使用情况。实际上这是一个重要的高考考点：
1. I can’t believe he was that good an actor. 我简直不敢相信他是那么好的一位演员。（引自英语语法网：http://www.yygrammar.com/Article/200905/1198.html）
2. I make $2,000 a week, 60 surely won't make ______ difference to me. (四川高考—2012-16)
A. that a big                              B. a that big        
C. big a that                             D. that big a
3. —Now that you like the computer so much. Why not buy it?
—Well, I can’t afford ______computer.（高考模拟题）
A. that expensive a               B. a that expensive

C. that an expensive               D. an expensive that