Guidance on a bike for my nephew

[NHAero]

He lives in SF, has been riding road with friends, has a 60cm Trek Emonda ALR (don't know the model number). He's coming east for a month or two and planning to ship that bike here (MA) where both my sisters have houses on Cape Cod. He's WFH until at least the end of 2020. He's been training for a triathlon (I hear 2nd hand from my sister).

He's thinking about leaving the Emonda at the Cape, and picking up another road bike. He is looking for disc brakes. Doesn't want electronic. Guessing those Treks come with Shimano 2x11. I haven't gotten input from him about max tire width he'd like to run - the Emonda spec says 26mm is max. He's not a bike afficianado, just a big strong 26 year old who has gotten into biking with great enthusiasm.

If I were to help him find a bike, new or used (would start here), what would I be looking for? He said carbon or aluminum, but I wouldn't let that limit me. The 60cm Emonda has a 58.6cm TT.

Thoughts?