According to Fallout wiki...
In Fallout: New Vegas, there is an Enclave Eyebot. This, however, is the only Enclave presence in New Vegas.
So...problem solved about the Enclave, and possibly the trailer (Unless *Dramatic pause* there is a second one!!!!?!?)
As for why it's there, who cares? Computers go wrong, wires get crossed, and shit happens. All you need to know is that an Enclave Eyebot went rouge, and ended up in vegas. Who knows, maybe it intended too, maybe try to retire peacefully after the Enclave pressence in the east coast was defeated.