A big problem with an unlocked framerate is the physics system, which you can generally solve in two ways:

1. You tie the physics to the framerate. Problem is that this introduces all sorts of weird behavior, caused by rounding errors and frequency of collision checks. For example, objects could start glitching through thin walls if their framerate is low because collisions are checked less often.
2. You run the physics at a fixed framerate. This solves a lot of problem with the first approach, but also means that you have to put in effort to mask the fixed framerate through interpolation/extrapolation if you still want to keep the actual framerate unlocked.

So Wolfenstein New Order probably went with the first approach, made sure their physics system stays stable within a certain FPS range (30-60), and then locked the FPS beyond that.