You made pretense and offer of evidence by making the claim itself. You claimed Mormons were polytheists, refused to support the claim, got refuted by the faith's own doctrine, and now you handwave it away with an excuse.

It is no different than making a false accusation. Since you not only refuse to provide evidence, but have been utterly refuted by the ideology in question, one can only rationally conclude that your idea stems from irrational fear and/or hatred towards something you aren't willing (or aren't able) to understand. What, are you afraid that you won't have as much money on your collection plate next Sunday? Do you see them as competition and must resort to base slander to try to discredit them?

Mormonism is no more or less a "cult" than any other religion, Christian or otherwise. However, if Mormonism is a "cult", then they portray attributes that are distinctively out of the ordinary for cults:

Cults typically do not share information about themselves freely. Mormons do.

Cults typically do not allow non-members entry into their meeting places. Mormons do.

Cults typically demand that members associate with other members only. Mormons are encouraged to associate with members and non-members.

Cults typically do not proselytize and tend to be secretive about their recruitment process. Mormons proselytize heavily.

Cults typically foster dependence upon the cult apparatus and seek to control the information members acquire. Mormons are encouraged to learn and attain an education, as they believe that the knowledge and experience one gains in their mortal life is the only thing that they will retain after death (as opposed to retention of material things).