Bolded part is the important one - good players will ALWAYS outperform any silly bot. People that bot are lazy or simply bad.
And in my opinion, botting is unforgivable. Whether it's someone you've raided with for a long time or not - it betrays an attitude to the game that I would not want in my team. As a guild- and raidleader myself, I would immediately remove this person from the team and the guild and announce it to the guild as well. Zero tolerance for this crap, doesn't matter if it violates ToS or not, it's pathetic and embarassing for the team and guild.