From the perspective of academic psychologists, this is true: "Substance use disorders (SUDs), as described in DSM-IV, are part of a class of disorders (substance-related disorders) that are “related to the taking of a drug of abuse (including alcohol)” [1 p. 175]. Although the transition from DSM-IV to DSM-5 involves changes at multiple levels for SUDs, this basic definition remains unchanged [1,2]."

However, most likely readers of the article are likely unaware of the distinction (or may resist it), so the usage of the colloquial and informal definition of "drug" that excludes alcohol would help more people with alcohol use disorder find the article and learn about its main points.

[0] https://www.ncbi.nlm.nih.gov/books/NBK519702/