Culinary School in Sacramento

My brother is going to Rome for about six months for culinary school, leaving the U.S. the last week of September. I was checking flights for him, and it’s going to cost about $1700 if he books his return flight for six months down the road, instead of, say, scheduling his return ticket a month later but not using it until springtime. I realize there are a lot of really sticky regulations with international flights, especially flying back into the U.S., and I got to wondering if my brother’s ticket would be tagged as suspicious if he didn’t use his return flight on this ticket but booked another round-trip ticket later. He won’t be coming back to the States for six months, but we don’t have the extra $600 we’d have to pay to schedule his return trip for April–the rate quoted for a late October return was just over $1100. What should my brother do to keep from being tagged as suspicious in booking his flight? Any links for first-time international travelers would be awesome.