It's really just an OCD thing I have about 3 lefties on the same line. But I also think he could do very well there (and as a side benefit, seeing him play a top 6 role could help determine if Pominville is expendable), and Nino could continue to take advantage of favorable matchups on the 3rd line. If both he and Coyle take another step forward, that's one of the best 3rd lines in the league.
To the underlined point above, let's say Fontaine puts up ~20 goals and ~45-50 points, playing a top6 role. Assuming that Graovac has another progressive season in Iowa this year, and is on track to take the #3C spot in 2016-17; this would push Coyle to the RW where Fontaine has shown he belongs. Pominville may now become expendable.
I hope that's some sort of logical.