It’s litterally against the EULA:
Harassment, “griefing,” abusive behavior or chat, conduct intended to unreasonably undermine or disrupt the Game experiences of others, deliberate inactivity or disconnecting, and/or any other activity which violates Blizzard’s Code of Conduct or In-Game Policies.
We all have been afk in a BG at some point but the rules use tthe word “unreasonable” for these things. It’s not unreasonable to go to the toilet but it certainly is unreasonable to stand afk over and over in bg after bg no matter if you use a click bot or not.