Those endlessly pontificating about "aviate first" and harping on about best glide speed seem to be blithely ignoring the fact that all this was all happening over a densely built-up city. The only unbuilt ground for miles around is steeply wooded hillside; the rivers have bridges over them. Achieving and maintaining best glide speed is pretty academic in terms of outcome here, it wouldn't have taken them anywhere better. It could arguably even have been less optimal; I think on balance I'd rather take an aircraft smashing into my house with the least energy possible if it's going to happen at all.
Incidentally, there is one patch of relatively flat ground without buildings on it, mainly comprising allotment-style gardens, and it is right on the other side of the river where they came down. It's possible they were aiming for that, rather than the river itself.