The DFDR seems to sit on a shelf attached to the pressure bulkhead. No part of that shelf appears with the chassis on the bottom.
We also see that the platform that joins the chassis to the memory module has a slight bend up relative to its position when mounted. It may be worth asking how that bend got there. Possibly the lower skin was pushed up by the water, perhaps bending at the bulkhead so that the first hit on the DFDR would be on the portion farthest from the bulkhead. Alternatively an access panel came loose and was pushed by the water against the DFDR housing. That bend in the DFDR platform may have been what popped the memory module loose in the milliseconds before the chassis parted company with its shelf. How the memory module ricocheted inside the remainder of the tailcone is open, but I would not be surprised if it lodged into some component before the entire tailcone came apart. Some of us can remember the complex path a certain oxygen bottle took on its way out of a 747.
It might be worth checking the recovered tailcone parts under the fin for memory module sized dings or red paint smears. Worst case scenario is that it lodged there for an extended period before coming loose miles away from the wreck.