I'm going to be shouted down here but whatever, my opinion.
I personally find it disgusting that valve take a cut from non-digital items such as merchandise. I'm sorry Frontier but that for me would have been a deal breaker and if that was the only deal they offered, I'd have kept the game off steam.
I have no problems with them taking a cut of digital copies of the game but this is too much. imo of course
Maybe wait until someone from FD clarifies that a bit more Steve? Only confirmations I see are from community moderators that shouldn't really be speaking for Frontier.