While I disproportionally use Ruby and JavaScript on a daily basis, this statement is referring to a specific type of (common) error, which is largely alleviated by the use of static typing, and therefore not exactly untrue.
I didn't take it as a disparaging of dynamic typing.
My guess is that rather than give an exhaustive list, the author wanted to give an example of a familiar language _without_ static typing. As Haxe is more similar to ECMAScript than Python, Ruby, Lua etc. - it's the most appropriate comparison.
As a person who likes (the good parts of) JavaScript, I read it as trying to appeal to me with promises of less debug time.
I didn't take it as a disparaging of dynamic typing.