If you mean the hole near the back strap mount ?? that's where the original mount point was, it's been moved more onto the heal (I suspect to help the balance), though may get in the way a bit if you like to play up that high allot, but seems it would help a little with the slight neck heavy issue ??
The better guitars are put together with glue that's designed to come apart (at a temperature a bit above a hot car boot in summer was what the guy (Jim Williams) who taught me how to build them told us). So you can heat it up (heat lamps, alcohol burner ??) and then "carefully" pull it apart. Early instruments, I think they used animal glue which will also heat apart. We used Tightbond, Aliphatic PVA glue. Probably the most common pull apart is removing the fingerboard.