What is the Chinese origin of “kai shao”
It's just 介紹.


Following the blog post, it mentions Philippines culture.
Looking up languages of the Philippines, we get Hokkien as a major Chinese topolect.
Looking up 介紹 in Wiktionary, the Hokkien Romanisation is kài-siāu.


The blog post spelling it as "kai shao" is just not following a particular topolect's Romanisation, but just spelling it out by ear.