The helicopter is to avoid the flow of fixed-wing traffic.
In general, general aviation airplanes fly a left-hand pattern at 1,000foot AGL. A helicopter has a lot of options when flying a pattern at an uncontrolled airport. For students, a common option will be a 500-foot AGL pattern with right traffic. However, any pattern that avoids the 1000 AGL pattern of fixed-wing aircraft is appropriate. Outside of student environment, helicopters will perform approaches directly to their intended landing area, avoiding the fixed wing traffic. Due to obstructions, noise abatement, or other reasons, some airports have right-hand traffic requirements, so check with the Chart Supplement (f/k/a Airport Directory) for that specific airport.
14 CFR 91.126 Operating on or in the vicinity of an airport in Class G airspace
FAA AC 90-66B Non-Towered Airport Flight Operations