[…]and quite frankly I’m surprised it hasn’t been officially released on 4K.
Well, your surprise might be supported by many other titles, such as:
Se7en (announced and allegedly scanned in 8K, but beware of also Fincher’s remastering fetishes so who knows if it will really be any better than what we already have. I highly doubt it)
The Game (two Blu-rays available, but either with a dated master or ugly orange & teal color grading)
American Beauty (the Blu-ray also is rather mediocre)
Panic Room (not even an official Blu-ray release, just some bootleg and HDTV/Web-DL rips floating around)
8mm (even the BD-release took ages)
Girl with a pearl earring
The list is long, actually …