This is the official tow-line (official policy), but in practice, as long as you are travelling together, there are no issues for ticketing for a friend.
The policy is there to prevent mileage resellers from gaming the system.
I have done it several times (booked awards and travelled together with my GF), international to Sydney/Bangkok and domestic to Hiroshima/Sapporo.
No questions asked. I know it is a risk though....