That's because DFL requires an exact date that all involved parties agree on if the time between two matches for one of the teams is above the threshold of 48 hours. The crux is that there ar more than just DFL and both clubs (Hoffenheim allegedly have been very cooperative) but also local authorities, stadium operators, security services (including police) and "countless other services" with a say, according to Köln's Sports CEO Christian Keller. He stated that none of the discussed options (31st Oct, 18th Jan or another mid-week date in early 2023 got green light by all parties involved.
Quite embarassing for one of the biggest sports league on this planet.
Why not accepting a simple match cancellation and then looking for another date - under much less pressure. Next week it had been known how many dates had been avaiable with three months to plan and prepare.
Various leagues in Europe seem to manage that, in some places it's common practice.
Let's see if it doesn't hurt Köln too much on Sunday and also on Thursday, as they must win against OGC to keep their European campaign alive.