RTW tickets are most certaintly cheaper for C/F. Compare the following:

LAX-SYD (return) CROX fare:$12275
DSPCL fare: $9218

RTW LAX-SYD-(stop in SIN)-LHR-IAD-LAX fare ALL in Business Class (drum roll please): $7650

RTW book into D class and you could possibly upgrade to F on the UA legs

Full Y fare LAX-SYD (full fare coach, no restrictions) $6622

So if your friend has time (and it sounds like they do) and enjoys flying, tell them to see the world and fly in comfort for about what you'd be paying for a no restrictions coach ticket

ETA: on top of the $$ if your friend is a mileage junkie, that RTW trip is 24123 miles, which would net: 36185 base EQM/RDM (D fare bonus) plus if they are a 1p/1k an additional 24123 bonus RDMs for a total 60308 RDM/ 36185 EQMs