This is the principle of false equivalency - treating propaganda, vapid opinions, and just plain falsities with the same weight as facts, in the aim of being "fair and balanced." Letting the CIA, NSA, others speak at conferences where they are there to spread their own propaganda and to then treat these presentations as valuable facts is intellectually dishonest at best.
There is a time when various people need to be shunned to give them a wake-up-call, and not allowing these jerks to take time at our conferences.
The CIA fucking spied on the fucking Congress and made up "evidence" to turn over to Eric Holder to prosecute congressional staffers. Because they didn't like the investigation into plainly illegal torture.
These people need to be shunned and locked out, not catered to. Many need to be in jail at the very least.