Why is Dr. Grundmann Grouping Kratom in with Hallucinogens in his newest study?

SITSA has not moved since July. The thing that worries me though, is that Oliver Grundmann published research grouping kratom with hallucinogens. Specifically, Ayuhuasca which is made of two plants, one containing DMT which is a schedule 1 drug. If anyone can explain to me WHY they would group kratom with Ayuhuasca and Salvia divinorum besides the fact that all three share an indole tryptamine structure, I'd love to know. Because if SITSA did pass, we would be fucked based on that right there. If I'm wrong, please show me how because this makes me nervous. Specifically the Abstract says: A rising awareness of natural products with hallucinogenic properties and their potential for abuse in recent years has led to the wider introduction of traditionally used medicines to the Western world. Among them are three plant extracts that present various medicinal properties. Extracts from Salvia divinorum (Diviner's sage), Mitragyna speciosa (Kratom), and Banisteriopsis caapi and Psychotria viridis (Ayahuasca) have gained interest both among public health and legal officials due to increased reports of their use for recreational purposes. ***Pharmacology and Structure-Activity Relationship of Natural Products With Psychoactive Effects From Salvia divinorum , Mitragyna speciosa , and Ayahuasca. https://www.researchgate.net/publication/316372430_Pharmacology_and_Structure-Activity_Relationship_of_Natural_Products_With_Psychoactive_Effects_From_Salvia_divinorum_Mitragyna_speciosa_and_Ayahuasca