The first review posted by the buyer and the seller will still be blind. That’s the reason why it is called a “blind review”. The buyer will initiate the process by first posting a review, after which the seller will be given the option to post their review (at this time, the seller will not be able to see the review that the buyer has posted, which is why it will still be a blind review system).
The fact that the seller will be able to respond to the review posted by the buyer AFTER it appears on their gig/profile won’t make it any less blind imo. If the first review posted by the seller were to somehow disappear after they respond to the buyer review, one could argue that it is not a blind review anymore. But, this won’t be the case.
Sellers can still look like fools in the first review (when there is a huge mismatch between the reviews of the seller and the buyer). While being able to respond to the buyer’s review (to possibly defend their first review which might otherwise put them in a very awkward position) will be awesome, it will still not be the same as it was before the blind review system came along.