The head-sock ban was independent of the new helmets. A review of that specific item had been under way. I agree that it shouldn't have been approved in the first place, but the rule in question (ban on non-essential components) is a judgement call. It's a good rule, but it is hard to apply and needs consideration. Had Specialized introduced it in the beginning of the year, I hope they would have taken their time to review it before approving it, but on the eve of the Tour I think they may have allowed it without any careful review.
The other rule regarding helmets, with a limit on their dimensions, is a relatively new rule that is such a hard guideline that you are asking for. So the new helmets are within the allowed dimensions, and thus approved.
They just didn't foresee how much that regulation allowed, and will now review the rule in question. I hope they will take their take, and wait with a new rule-set until after the season is over. Then manufacturers have the winter to adjust.