Personally, I already met the comm requirement long before the dungeon requirement when I was aiming for the mentor status, but I'd never straight up ask for comms.

Even if you enjoy helping others, I don't think there's any way to convey a desire for comms that isn't going to come across as selfish, since you don't need comms or the mentor status to help your fellow players. Even if your goal for mentor status is truly altruistic and motivated purely by the desire to help others, it's better to just tell the truth but not the whole truth and say you're just trying to help. ;p