I vote "no." By that I mean bigfoot is not official US government knowledge. That is a very different thing than whether or not specific employees of certain agencies have personal knowledge or not. In other words, if you went to work for USFS in any ranger district in the US, not one bit of your new employee orientation would say a) to deny knowledge of bigfoot to the public but b) here's the info in the employee handbook. THAT is what "government knowing" means in the real world. .. and I say "no", they do not have institutional or organizational knowledge.
MIB