If BOB was not available to all the people that play the game then using this tool would be cheating. Since there is a thread that makes BOB available, even allows users a forum to suggest improvements, then it is a community developed tool that enhances the game play.
If I were playing online poker and I developed a 'tool' that would show me all the players cards that's cheating. If it was made available to all the players no one would play anymore but it's no longer cheating.
My two cents anyway...
BTW play both with and without BOB (there isn't a firefox client for my phone, yet)