When I took my Shinko Golden Boy in to Cycle Gear to have them mount it on my front wheel they refused to do it even though the tread pattern is symmetrical and there is no directional arrow on the sidewall. When I asked why, they said it was company policy so I asked to speak with a manager but they said there wasn't one on duty. I then took it to an independent shop and they mounted it without issue.
I remember someone on here said that if you mount a directional rear tire on the front, then you should reverse the rotation of it. Something about the different forces that the front and rear tires see, i.e., driving forces vs braking forces. That all that I can offer to this topic.