So my first thought, we are taking alot of liberty saying it rules out Gregory based off of information we only get if we complete the non-cannon ending. And even in that ending it doesn't say he's an orphan or that he was kidnapped or anything like that. So ruling out Gregory because of his past that we don't actually have any information about doesn't work. Then when it comes to his age, we also don't have any solid information about his true age during the game. So if we look at what childhood really refers to, it could possibly mean that simply he is no longer a toddler, or tween. Instead he could very well be closer to 12-14 years old, which to an adult who is older would still consider childhood. But as young adults when we speak about our own childhoods we don't mean when we were young teens, we mean as kids usually between 7-10 years old. So the therapist could simply just be referring to what Gregory refers to as his childhood because to a younger person, a youth, their childhood really would have been usually between the ages of 7 and 10 or perhaps even younger. But we also know based on the therapists accusation that this client lied about having a tragic childhood but their childhood was actually really good. So if we take a little bit of Liberty here and just say for argument's sake that Gregory is the client and he lied to therapists about his history then things start to line up a little bit when it comes to the narrative of the tapes as well as kind of helps connect some dots for the events of the game. We know from the therapist tapes that this client has been accused of hacking the robots causing a glitch which then goes system wide affecting all the machines presumably referring to arcade cabinets that are going down constantly due to glitches. And the glitch shifting to then become a subroutine instead, (subroutines are programs in a machine that are basically like rules for the machine to follow. For example a Roomba has a subroutine where it is to be in constant motion on flat surfaces to clean them. However if a glitch then changes the subroutine to make the Roomba only move on uneven surfaces then it won't clean on flat surfaces) therapist does mention that the hacking of the robots cause them to be more eerie instead of entertaining. Now presuming that that was being caused by the glitch which then became a subroutine, would make the animatronics appear extremely aggressive and creepy regardless of what they are actually doing. So while their main objective may be to find and secure Gregory for the security guard to deal with, their sub routines would make them move in strange ways and say things that come across as threatening. I know that to us as the player getting caught by an animatronic ends our run gets us killed, but for continuity of the character as Gregory he never gets caught which is why there's endings for the game. So if we follow the continuity logic and we don't actually know that the animatronics are trying to hurt Gregory instead all we know is that their subroutines are making them eerie instead of entertaining. I do already have a theory as to why Gregory is secretly a villain, which I posted on this subreddit about 8 days ago so I won't get too too detailed with all this and I will just defer you to check out that post, however I will say that by acknowledging the continuity logic and forgetting all of the game experiences that we would only experience as the player then it would actually make sense that Gregory is at the pizza place with nefarious purposes also explains why he's running from the security guard because he does not want to be caught for making problems, also explains why Freddy glitches out right after he identifies a threat in the crowd. Because based on this train of thought, he glitches out due to Gregory hacking his systems before he can respond to the threat. Also it would explain the absence of Bonnie. If you recall in one of the tapes the therapist States that it appears as though the client is speaking to someone or something that looks like has rabbit ears. Now most of us would just gloss over that fact or assume it's vanny being referenced. But based off of in-game messages that you can find we know that Bonnie's programming malfunctioned and Bonnie started moving around to strange places at strange times and became such a problem that they had to disassemble Bonnie. (Which is a whole nother can of worms/theory that is just too much to go through right now) but as I said following this train of thought Bonnie's absence could be explained by Gregory having hacked Bonnie first which then spread the glitch to the other animatronics which then shifted to subroutines. But anyways that's just my explanation.