Then what is to happen to those that simply went AFK too long? The first thing that happens is the switch to spec. When that person comes back what if they auto team and end up on the opposite. They'll get banned. The reason you probably see a lot of spectators is because the server puts them there if they go AFK. If someone is spec too long the server removes them. As long as there are people in the server that are immune to auto balance you can never expect the teams to be balanced and really shouldn't expect other players to react any differently. Just because they didn't subscribe is no reason they should be banned. The rule may have worked in NS or TFC but I don't think it applies here very well.
If you are going to ban people for something so trivial it should be in the MOTD. I like this place because everyone is overall friendly. I don't want to sit and listen to an admin threaten every person who goes spec. I want to have fun. I enjoy the fact that for the most part the admins want that same thing. Going spec isn't hurting anyone and the server in its own automated way will take care of that. Going out of your way to enforce that rule is just going create more problems when none existed to begin with.