If I got it right, they are basically planning to do a search of 20nm around LKP.
That sounds like a plan !
From my point of view a very reasonable approach.
Seems to take into consideration that any travel much beyond 20nm after upset is not very likely, given the timeframe of < 5mins and the typical aircraft attitude / speed / flight path after a major upset.
Plus the fact that the Northern half of the circle has already been searched rather intensely and now extending to the South.
Somehow I'm pretty confident that they will find something....
If not there must be a story after 2:15, which is not really supported by the last ACARS message missing.
Let's cross fingers !!!