The OP's friend sounds like a perfect candidate for a custom frame . . . Or . . . An older mountain bike conversion.

Back in the 1990s, rigid mountain bikes often had short seat tubes and long top tubes, which is the geometry your friend needs. This was for lots of crotch clearance plus a racy position. Their head tubes were low, allowing plenty of saddle to bar drop (because they didn't need to accommodate suspension forks). They had 26" wheels, of course. The higher end models were quite light and of high quality. With road tires, they are plenty speedy. They can be converted to drop bars, or you can cut the bars a bit narrower and fit bar ends for a variety of hand positions. In the Classic & Vintage forum there is a long running thread about Vintage MTB conversions. You might check that out.

The nice thing is, a 1990s rigid MTB is usually quite inexpensive. Even one that was close to top of the line back then.