My advice. Tell your friend to form groups that are made up of only inquisitors. The more of a class in a group the better the odds of loot for that class dropping.
That being said. It sounds to me like your friend just got very unlucky. If hes really considering quitting the game because he didnt get any loot in 3 tier 1 runs this probably isnt the game for him.
First off, that's wrong. If you have 4 inqs, you have a 99% chance for that gear. 3 inqs is 50%. The loot bias is only dependent on what classes are there not how many. IE, 2 inqs and 2 bh's would be 50/50 beacuse there are only 2 classes there, but 2inqs, 1 bh and 1 agent would be 33/33/33 because there is 3 classes.
Now, I will say this, your friend is unlucky atm, but not nearly as unlucky as one of my former guildlies. Before 1.2 and the loot bias and when FP's still had daily lockouts, he had to run FE 17 times before an agent chestpiece token dropped for him.