The injury worry is a non-starter. Injuries can happen at anytime, in practice, in training camp, in a pre-season game, during a regular season game, during a play-off. The only time a coach should consider benching a player due to injury is in a game where there is no possibility of changing the outcome. I even question resting players at the end of the season.
As far as this game deciding who should be 2nd or 3rd. This shouldn't be a factor in the decision to play them ahead of Marcus. Typically, starters use at least a half of the second exhibition game to get into game mode. 2nd and 3rd string can be determined on the practice field if necessary.
The only true factor should be if the offense is that far ahead in their prep. Based on the comments from Millar and others that seems to be case. But as they say, the proof will be in the pudding. If the riders come out and win game one there will be no questions asked. If they stumble as a result of the poor offense then the riders created the problem themselves. Based on the last years offense in the first 6 weeks they only demonstrated how good they could be twice. They should really consider do they want to put the extra pressure on Marcus. If he comes out slow, there will be the media and fan yelling and screaming for Durant and/or Jyles.