Old & New--
Fact: Other posts have dismissed carbon fiber as a possibility simply because the person in question weighs 300 lbs.
Fact: I only have asked not to dismiss carbon fiber out-of-hand simply because (see: post #17)
Fact: I am 300 lbs too...or rather I was when I first purchased my cf frame.
Fact: My frame has not cracked or failed me in 3,500+ miles
Fact: There are cheap frames in any material, steel, titanium, aluminum, carbon fiber
Conclusion: It is therefore ignorant (def: not knowing) to dismiss cf as a possibility simply because you think it will not work for a 300 lb rider when it is demonstrated to work for another 300 lb rider.
Opinion: Do I recommend carbon fiber? I don't know the guy. I recommend a bike that fits, is sturdy, and is comfortable. At least give the guy (or girl) choices and reliable, truthful information. If they want to blow a wad of cash...who are we to say "no"?