This is a good point. Thanks for reading critically. Another thing to consider is that author is from Colorado Christian University, which has a strict moral code for all its students. From Wikipedia:
All traditional undergraduate students are required to sign the Lifestyle Covenant to attend Colorado Christian University. By signing this document, students commit to themselves and each other that they will pursue the challenge of living a life defined by a higher standard. The Lifestyle Covenant states a commitment “to educate men and women in the process of integrating their faith and education. This agreement also expresses our commitment to providing an atmosphere for study, personal exploration, involvement in interpersonal relationships, spiritual life, and growth that is conducive to students achieving goals, while enjoying living and learning in community”. Students not signing the covenant are subject to immediate dismissal or suspension.
There’s nothing wrong with a “lifestyle covenant,” of course. If that’s what you want from a college, you can choose that.
But recreational marijuana use has often been seen as an issue of moral failing, while alcohol, craft beer and wine is often celebrated (you can even get alcohol in church as part of Mass!)
So I wonder how much is a legal issue for the author, and how much is influenced by his own moral code. I have no idea. So it might make sense for him as an opinion writer to be upfront about his own personal biases.