Even before the Mentor thing, I would, especially as a tank and saw bonus, would stop just outside the boss room to give simple explanations. I have no keyboard, so the typing is moderately slow. However, you get people who feel that if they engage, it'll trigger me to act, in which it does. Sadly, the new person mess up a mechanic then he becomes an idiot.
After a while, I just stopped trying, because if I'm on healer, dps, or tank, others will pull regardless of where I'm standing. Just yesterday, I typed, "Wait!". As I was typing, the tank still pulled after like 3 seconds. When I mentioned that I was trying to explain something, he said that it's not our fault that the newb is a newb. The tank had a crown.