DL and NW filed for BK on the same day on the same NYC courthouse steps, yet denied they would ever merge. Then DL hired the former NW CEO...who also denied DL would merge with NW.
Then DL merged with NW.
DB is playing two angles here, and you have to give him credit for it.
If JB somehow ends up a stand alone, he knows he will remain in ponzi scheme endless growth mode for many years to come as legacy airlines continue to gift capacity and RASM to him. Maybe even enough to make a go of it with widebodies. Filled up with AA pax in any case, and every flag carrier in existence, even if AMR only gets a portion of their term sheet fantasy, JB could win big, temporarily.
The other side of the coin is DB knows AA and SW want between all and half of JB, and DL sees the JFK T5 as either a nice addition to T4, or a nice solution to a trade to end up in T8.
Either way, by staying the course he feels he will personally win big. If there's no merger, he salivates over more "growth" others will gift him and the positive yield environment that he can grow in despite JB barfing massive YoY capacity into the system. If there is a JB merger/buyout/fragmentaion, DB can drive up the price later by essentially agressively doing nothing now.