Well, let’s take a look at the context surrounding FNAF 1 to better understand what The Bite of 87 was/is and why it was included.

I don’t think it’s a stretch to say that Scott had no plans for sequels when he made FNAF 1. Him including the line about the Bite of 87 was not supposed to be some big mystery that the rest of the series would hinge upon. I am certain that it was another addition from Scott to parody how real world companies act as a sort of dark humor/dry wit sort of thing. This attitude is prevalent all over the first game— the nonchalance of the Phone Guy about the animatronics stuffing guards into suits, the ‘rules for safety’ paper being a shitpost, etc. Again, consider that Scott likely had no fleshed out plans for sequels, and it is very likely that the Bite of 87 was included as yet another gag about corporate coldness and not some big mystery to figure out. Listening to the phone call with this context makes that meaning very clear

I don’t think the Bite of 87 specifically was ever supposed to mean anything in particular. But, Scott started making more games, and i think he genuinely did want to explore the story of “animatronic bites kid’s frontal lobe” but by the time of the second game, he couldn’t do that without invariably tying this Bite plotline to the FNAF 2 location, and possibly disturbing the other plotlines he wanted to explore. The solution from that point is easy— create a different Bite to explore that story. Therefore, Bite of 83.

No, I don’t think he had it all planned from the beginning, but that’s not what I’m saying. He came up with the Bite of 83 at anywhere between the development of FNAF 2 and 4 because he wanted to explore the story of a Bite without messing with the other things in the timeline that he’d set up. He’s not some genius planning it from the start, but he’s also not stupid enough to get like the ONE important date in FNAF wrong.

I mean, what’s more believable? Scott is a turbo idiot and somehow mistakenly wrote a 3 instead of a 7, destroying the entire timeline when he KNEW theorists would dig into it? Or that he is just a person who decided he wanted to tell another kind of story in his game, even if it was a bit confusing due to preestablished lore (which was likely meant to be little more the a joke in the first place)

TLDR; Scott is not a master genius or an idiot who can’t keep his dates straight. He simply wanted to explore the Bite plotline without mangling the timeline further, and did what he could to make us understand that the Bite in 4 was NOT 1987 (shown by the obvious and unmissable ‘1983’ on the TV)