I opposed to my adopted Indian friend having an Indian wedding and I'm going to tell her so.
Why do you think having an Indian wedding is a problem?
In my opinion weddings are a scam.
I understand that you think weddings are a scam, but you shouldn't tell others what to do for their special day. Let her enjoy her day any way that she wants.
I want to encourage my friend to not opt for the wedding and instead publish an essay about why weddings are a scam.
It's your friends marriage and you should stay out of it and not tell her how her special day should be celebrated. Sounds to me you are the one who should write the essay about weddings being a scam, which genuinely would be quite interesting.