Security Breach Ruin Theory

TLDR: It's suspicious that we never get confirmation that the person we are talking to after the reveal of the mimic is actually Gregory. The talking over the walkie-talkie is glitchy much like the mimic was right before the reveal. He also weirdly transitions from speaking over the walkie-talkie to that of the elevator intercom which I can't imagine is particularly easy to do not does it make much sense given he could just continue talking over the walkie-talkie. Also weird dialogue given by Gregory during the mimic chase scene implies that he is somehow able to see us during the chase which I really don't understand how it would be possible.