I have never seen a male officiant wear a boutonniere. The Protestant ones usually wear robes, sometimes with a color stole. Ours had one custom made in our wedding colors!
Our officiant wore one. The same as all the groomsmen. But, our officiant was also my "third" grandpa.. I don't know that I would have done it for someone else that I wasn't close to.
We also had them for both dads.
Dh's was a little different than everyone elses, but this is us with our officiant.