I don't believe the leaked document indicated government agents or personnel planned to kill leaders via suppressed sniper fire. You're talking about page 61 of this document I assume? http://www.justiceonline.org/fbi_files_ows
That document doesn't say that the FBI was trying to assassinate the Occupy Houston leaders. It says the FBI uncovered some other party's plot (apparently, organized crime) to do that. Ryan Shapiro sued to find who the snipers were but was eventually denied. http://www.courthousenews.com/2015/02/06/fbi-gets-ok-on-alle...
See the article linked at the end of my previous post:
> The FBI was right to withhold records about an alleged murder plot targeting the leaders of Occupy Houston, to protect its informants, a federal judge ruled.
(U) Law Enforcement Sensitive: This information is the property of the FBI and may be distributed to
state, tribal, or local government law enforcement officials with a need-to-know. Further distribution
without FBI authorization is prohibited. Precautions should be taken to ensure this information is stored
and/or destroyed in a manner that precludes unauthorized access.