When first approached, Thomas is training a group of initiates in the training room. Watching his exercise nets 500 XP, +5% to Melee Weapons and Unarmed skills (only the 500 XP are noted in the text window).
The following is based on Fallout cut content and has not been confirmed by canon sources.
“Why I ought to throw you right out of my room, but I'm a nice old man. The elders said no new initiate training but...I might be able to help. They probably didn't have you in mid when they said that. What are you looking to train in?”— Thomas