There are so many variables here it is almost not worth commenting on them.
No one said that they would sell their house and move right away.
No one knows that they will sell it at all in the next year.
They could sell it and rent for a couple of years.
They could buy the house for themselves in Greenwich which would be a permanent base, but they don't need to live there right away.
I can see however that this is a message for Kraft, since, when the Brookline house was built, Brady was overtly discussing his relationship with Kraft. But perhaps there's more to it--maybe Brady built it with other post-football goals in mind.
I will say this, the whole situation is crazy when you realize we don't have Steve Young backing up Brady.