There is a list of good looking wood that can be used for deck board and don't think pressure treated 2x6 is on it. We do it all the time but people have to understand that it has been graded for structural service. It will have ugle knots, cracks, cants, pitch runs and they have been cut from all parts of a tree. They may or may not have been dried before pressure treatment and may have absorbed more or less of the pressure treatment.
I would think you treat a deck with a perservitive to maintain the beauty of the wood.
I would have reccomended a solid stain after a nice hot summer evan if that means waiting 16 months.