It wasn't voted out of the blue. There was extensive discussion prior to votes (including weekly telecons for months solely dedicated to contracts). So how do you measure consensus if not by a vote after extensive discussion, leaving everyone to voice their opinion, come up with alternatives and propose polls?

And sustained opposition does not necessarily mean lack of consensus either. WG21 heard the opposition and decided that constracts belong in the proposed draft despite of that opposition. It is very rare that a new feature does not get opposition, even a sustained one.

Now it is clear that there is no consensus between WG21 and the national bodies (although they overlap), but there is clear consensus within WG21.