Post hoc propter hoc

Hello! My question will be a mix of English, Latin and Portuguese, so please bear with me.

I read a text where the writer thinks it is unnecessary to use "ergo" in the expression "post hoc (ergo) propter hoc". I found this interesting and I wanted to ask about it from you. Is "ergo" useless in the expression (i.e. name of a logical fallacy)?

Here is the citation:
Post hoc propter hoc