Practical Travel Safety Issues - Haitian visiting U.S. on 1-way ticket

I won't get into the background here, but my family has connections with Haiti, and a Haitian friend is to visit my parents in the U.S.; he has a 6-month visa. My father booked him on a 1-way ticket; will this be a problem for U.S. immigration, or even boarding the flight? I found the Timatic information at http://www.staralliance.com/en/services/visa-and-health/ ; they say

Return/onward ticket is required to travel to the USA. (SEE

NOTE 46524)
NOTE 46524: Exempt are holders of a valid US visa.

Does this mean that if he has this visa, he doesn't need to have a return ticket at the time of this flight?

If he has the Visa before arriving to the airport and to the USA then based on what you have found he would appear to be fine. However, I would not go by what the airline has but call ICE and verify via them as the airline may not have up to date info.

The passenger may be put into a very embarrassing situation when attempting to fly. Check all possible details.

Just play it safe and get a refundable return ticket.

Thanks. My father was just keeping it flexible when he saw one-ways at reasonable fares. Now he'll find out when the friend wants to return and book a regular return.