My advice is to immediately rebrand as gracefully and effectively as possible and use all that activist energy to effect the transition.
They kind of have a point which doesn’t make them right, but they hold all the cards and you will lose this one and regret the wasted bandwidth.
They don't have a point based on basic common sense either, because this application isn't telling people to use amphetamines. It's a metaphor.
https://www.deadiversion.usdoj.gov/21cfr/cfr/1308/1308_12.ht...
Though, Schedule II means it has accepted medical uses, so it is not illegal. For instance, lots of kids are prescribed amphetamines for ADHD.
The part of the policy that actually references "controlled substances" only forbids apps that facilitate their sale by non-pharmacies.
I think the GGP has a point if you replace "controlled substances" with "illegal drugs." The reviewer obviously seems to think the terms are synonymous (which is false), and banned the app under the clause that forbids "encourag[ing] consumption of ... illegal drugs."
Leaving everything else aside, this reviewer pretty clearly failed to understand and reasonably apply the policy as written. Reference != promotion and "controlled substance" != "illegal drugs" (all illegal drugs are controlled substances, but the reverse is not true).