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
Your document is ambiguous, however the others are not. Please try not to cherry pick.
> 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.