The previous deadline was in November, so this is a delay by about a month. The NCC mentions that this is at the request of proponents (the bidding groups), but as with most things in this process they are delightfully vague about if it was one, some or all of the bidders that requested the additional time.
One new-ish piece of news in this is the confirmation of open houses for the proposals in January. It was suspected that it would be January or February for those, it is nice to have confirmation.
Back in April the NCC said the project is ahead of schedule by over a year, so an extra month at the proposal stage isn't likely to hurt things too much.
Read more on the LeBreton Flats coverage here.