I don't remember a specific rule that bans discussion of any individual topic but I did find this:
By agreeing to these rules, you warrant that you will not post any messages that are obscene, vulgar, sexually-oriented, hateful, threatening, or otherwise violative of any laws.
The above rule specifically says that no messages that violate any laws are allowed. However, merely talking about distilling or using cannabis doesn't violate any law. Free speech is protected in the bill of rights in the US constitution. Specific examples of speech that would be illegal would be any threats of violence against the President, or going into a crowded theater and yelling "fire" when there was no fire.
Being intoxicated by alcohol is a violation of law in many places. If you are going to ban talking about something because the activity itself, but not the speech, may be illegal, there are many posts that need to be taken down.
I think the rule above is reasonable. Interpreting any rule in an extreme way is not reasonable.