I understand the thought but don’t sell us on training camp is about icing the best team.
I understand your thinking, but training camp is about icing the best team for the entire season, not just opening night. Blanks, Vronkov, etc., can still be called up anytime without waiver concerns - injuries will happen even if it's a tame year for injuries. You keep Blanks up now and he gets injured, there is no depth behind them as the other D would have been claimed off waivers.
That's my thought, regardless of whether they have even a sniff of a playoff spot or not - contract management has to be a part of the puzzle.
If Blanks (or Vronkov or others) had played so well that CBJ could not send them down and face the "room" - then they would have made the opening day roster. They had a shot. Instead, I agree with you that they were better, but only marginally better than some other D who were kept on the opening day roster. Not enought of a difference to warrant Blanks being on the roster opening night in the interests of long-term roster management. Training camp matters, but if you are on the margins and if you are waiver-eligible, you've got to be appreciably better. He was fine but not appreciably better.