Both are used so both are correct, unless you're a prescriptivist, in which case a saying about stones and glass houses comes to mind.
The person you replied to used perfectly common and comprehensible English, so much so that you knew exactly how to "correct" them.
So the comment was grand and your prescriptivist response adds nothing of value. Hopefully you can see why this is true and reflect on why you felt the need to "correct" it.
There we go. The "response" was prescriptivist. The person posting it (me) and yourself are both somewhere in between the two. Now I think you're starting to get it.
Regardless, the original response was a just a joke referring to Stannis Baratheon (from Game of Thrones) saying it. I think some people read it that way. You didn't.