Excellent comments by Canadiest and fmitchell. This is called pseudoscientific apologetics. Incredible mind contorsions to justify a modern cult-specific interpretation of an ancient myth.
The particular adaptation of literalist creationism I was raised with was "Day age". Like this "Gap", it mixed up mythology, a bit of science the Watchtower could accept and apologetics to readapt the myth in a way that they believed was plausible. For instance, the "days" could be arbitrarily extended, considering that geology demonstrated how the Earth is old.
Still, they remained anti-evolution creationists and also continued to believe in other myths discredited by geology and basic physics, like Noah's flood. To them, humans only appeared less than 7k years ago, and the apocalypse may be tomorrow, you're pressed to avoid education and dedicate your life to preach the Watchtower doctrines instead. But, you may not have access to spiritual heaven, only to some unlikely earthly physical paradise.
The poor confused young fidels who see through their bullshit may temporarily wonder if they're the "annointed" few, to be judges in heaven, perhaps explaining why they see their wrongness. Yet those are considered to be long sealed (1914! and they play with that over the years since the end doesn't come, like for Jesus' "this generation shall not pass"). If these young ones dare partaking to their yearly Pantecost and take the "emblems" (the equivalent to Catholic communion, which to JWs is restricted to "the annointed"), even within their group they become freaks. Until they hopefully know better and leave the cult.
Like if the length of those days were the only issue with those myths, when there are so many other reasons to understand that they were only a stories for a very small ancient kingdom, a people who did not have science to investigate the past, but wanted to pass down culture into other generations (like every culture). The scribes who could write and copy those texts were a minority elite, just like the priests were.
Ironically, all those Christian cults call other "false religions" (everything else) "Babylon", but they're part of it.
