To eliminate competition.
First, however, they must buy Senators and Congresspersons.
If there were half a dozen large airframe manufacturers out there, one might successfully sue one of them for a very large amount. If there is only one left and they can portray themselves as primarily a defense contractor then there is not much chance that any one will ever be awarded a damage amount sufficient to cause them concern.
Sorry, I guess that sounded cynical.
Happiness is not seeing another trite Ste. Maarten photo all week long.