Earlier quoted context omitted.
Read the article. The title isn't a substitute for reading. It's short because your attention span is short.
You didn't answer my question. There's an advantage for using the long title "Alphago is not strong AI": less people will be angry at a perceived clickbait title. What's the advantage for using the short title "Alphago is not AI"?
I could guess that he didn't use a qualifier because there are many different ones and none universally accepted. Or, maybe he wanted to reach a non-tech audience who wouldn't know the difference between strong AI and AI.
There are plenty of good reasons, and reading the article clarifies the author's meaning.