I want to ignore the pitch dynamics, but Bladed won't let me use a zero time constant or instantaneous passive response
In Bladed, it is not possible to completely ignore pitch dynamics. This is because the rigorous structural dynamics approach requires that the pitch acceleration must be defined. This is necessary for getting the correct inertial loading in the structure. If the controller were to have the power to instantly change the pitch position or rate from one communication interval to the next, then the pitch acceleration would be undefined. So for this reason, it is not possible to ignore the pitch dynamics.
However, in version 4.6 and later, there is the possiblity to "Track External Hardware" in the pitch actuator UI. When using this, you can use the SetHardwarePitchAngle and SetHardwarePitchRate in the external controller API and the pitch actuator will track the hardware position and rate with a fully defined pitch motion (i.e. including acceleration)