I was playing at the very end of the game, fighting the legett or what ever, and during the fight i brought out the C-Finder, after killing the legett with it, i left the fort and the NCR General blew down the door, and mentioned that he saw some fireworks and said it was like the thumb of god coming down. just thought it was interesting to see and hear something like that.

Pretty sure he says that regardless of what you do if you power up the securitron army.

I think he is referring to the Boomers unloading their bomber on the dam...... not sure though.

I have not unlocked that weapon yet and he still says that line.

He's referring to your army of Securitons who wipe out everyone at The Fort (since you're battling at the Legate's Camp, NOT The Fort)