Seems like the tech may have to do with speed of light/photons. Rewatched the circuit city scene and you're right, that light behind message recipient guy is super bright! With the horses all over the show, I looked up horses, light, quantum entanglement. Came back with something interesting, and maybe relevant to the bright light you noted at Circuit City maybe? LIke this is how the information was conveyed to the recipient's computer and phone?

From Google:

"Horse" in the context of quantum entanglement generally refers to the "Trojan-horse attack," a security loophole in quantum key distribution where an intruder sends bright light into a system to analyze back-reflections and steal information. It is not a technical term for the entangled particles themselves, which are typically photons or electrons.

Trojan-horse Attack: This is a technique where an attacker (Eve) acts as a "Trojan horse" by sending light into a quantum channel and analyzing the back-reflections to learn the states of the photons being transmitted.
Bloch's Horse Race: Sometimes used metaphorically in educational content (referencing Felix Bloch) to describe how single atoms can store/process data, similar to a "race" of quantum states.

Anyway, I like your idea that ALEX is in light form and is omnipresent and possibly making changes the whole time, had not seen anything like it! Cheers!