Any argument that centers on the phrase "scientific theory" instantly goes in the trash and should tell you all you need to know about the person making it
Sometimes a common error, as people just have a rather ordinary interpretation on the meaning of the word "theory" and sometimes it's an intentional attempt of discrediting.
Words can mean different things in different contexts. A scientific theory is not the same as the general or ordinary every-day meaning of "theory".
Classic example and mistake by followers of creationist religions: "evolution is just a theory".
Well, what if I told you, that, for example, our modern electronic means of communication are part of the wide field of "information theory"?