My comment:
(a) His arguments may be familiar to Chinese, but not to me.
(b) "笔者大体赞同冷战史学者沈志华所作的中国出兵朝鲜的三点理由：第一，由台湾问题引发出对抗美国的革命激情；第二，根据国际分工为社会主义阵营承担责任和义务，第三，对国家安全和主权完整受到威胁的忧虑。"
"由台湾问题引发出对抗美国的革命激情" is an impossibility. President Harry S Truman, disgusted with Generalissimo Chiang Kai-shek, did not care about what happened to the latter.
(c) "如果中国不出兵参战，会发生什么。一是美国把战火烧向鸭绿江，战争在中国境内打响。这种可能性虽然较小，但并非不存在。当时麦克阿瑟就叫嚷着要进攻东北，并派飞机轰炸东北。正是因为麦氏的狂傲，使中共认识到新生的政权受到危险，遂做出出兵决定。假如美国把战火引向中国境内"
(i) The author confused cause with consequence. China intervened first; General MacArthur was maddened later.
(ii) US had not helped the Generalissimo fight the civil war with American ground force (a possibility entertained by CCP leadership), because it would be a quagmire. That is why US did not contemplate invading Manchuria, but did ponder nuclear weapons on China.
(d) Regarding the quotation above. Taiwan alone could have repelled any attempt to take Quemoy (also known as Kinmen), as it (Taiwan) did in October, 1949--not to mention the Taiwan proper. CCP lacked air force, navy and marine.