You could say that since everything that exists has consciousness to some degree or another, then yes, there remains "consciousness" in the atoms or substructure of demons, traitors, etc. What Samael Aun Weor was indicating (as had others before him) is the separation of the Being from the demon. In these statements, he was saying Essence to indicate the spark of unconditioned consciousness (the embryo of soul) that remains connected to the Innermost. A demon or "soulless" person no longer has that within them. They are instead an "empty shell." What remains is a program, a script, played out by the personality and the egos remaining. Yes: trapped within all of that are sparks of consciousness, but we cannot consider them as consciousness that has the capability of self-awareness, cognizance, remorse, etc. since the Essence is no longer there, the connection to the Being that in us prompts us towards the path and provokes our spiritual longings, remorse, etc. Without that connection, such "soulless" creatures are truly like sparks that drift away from the fire and vanish into the night.
“Nothing is easier than self-deceit. For what each man wishes, that he also believes.” —Demosthenes
"Do not worry; cultivate the habit of being happy." —Samael Aun Weor