LIHOP and MIHOP return from obscurity

Raise your hand if you are old enough to remember the heyday of these terms:

LIHOP ("Let it happen on purpose") – suggests that key individuals within the government had at least some foreknowledge of the attacks and deliberately ignored it or actively weakened United States' defenses to ensure the hijacked flights were not intercepted. Similar allegations were made about Pearl Harbor.

MIHOP ("Make/Made it happen on purpose") – that key individuals within the government planned the attacks and collaborated with, or framed, al-Qaeda in carrying them out. There is a range of opinions about how this might have been achieved. 

Those were the leading contenders in the conspiracy theories surrounding the events of 9/11.  Now the terms return in discussions of the White House Correspondents' Dinner shooting.  I've heard various suggestions that the event was staged, and have read strong denials.  Today I found this on Facebook:

If it's true that the police had been notified and that the shooter was on a watch list, then his being able to check into a D.C. hotel begins looking suspicious.