Thanks for the link.
From my quick read, doesn’t seem that they don’t support it. More of a caution to understand the risks involved with each App Store. For example, their comments regarding F-Droid are completely valid.
All you get from F-Droid is knowing that the developer adding a closed source third party library will likely get detected and the app won't get updated, but in exchange you're trusting people to build/sign the apps who have shown consistent untrustworthy behavior. You're also getting significantly delayed updated in many cases.
You can smell earwax?!