Jetblast
If this would be the final design of the R-66 (which I seriously doubt) it would not be the first helicopter with its "smoke-stacks" close to the ground. There are quite a few 500's out there, high or low-skid and there seems not to be of any problems as long as you stay away from the area under the tail-cone (which should be avoided in ANY case, as there are more imminent dangers there!!!) The enstrom 480, and Schweizer 330-series helicopters also has the pipes under the tail and haven't heard of anyone yet, with "jetblast" injuries.
This is most likely only the testbed for the engine that they have desided to go for in the new aircraft.