Great article, covers a lot of ground.
The rescheduling benefits may apply to the UK, but aren't particularly important to work on for the US.
In the US, access to research funding is a far larger issue than scheduling. The main benefit of rescheduling would likely be through its indirect benefits on access to funding, possibly from government agencies like the NIMH.
Also, both psilocybin and MDMA are in or beginning FDA Phase 3 trials, for likely approval ~2023 and 2021 respectively, after which they will be automatically rescheduled. So if you're in the US and you want to contribute to rescheduling, the way to do it is to fund the Phase 3 research via Heffter and MAPS. (It's possible that psilocybin and MDMA will be rescheduled, but that magic mushrooms and ecstasy will remain schedule I, but I don't think that's particularly worse based on my understanding.)
Source: I’ve talked with multiple researchers who are studying psychedelics.
Also, I recommend reading or listening to the book Acid Test if anyone here would like to learn more.