F/D not available
My latest QRH revision states:
Note:
1.If engaged, the autopilot disengages when α is greater than α prot.
2.If the FD bars are not available, use an initial pitch attitude up to 17.5 ° with full backstick, if necessary. If needed, to minimize the loss of height, increase this pitch attitude.
So, while the F/D is still available it is not in the desired mode, so I would have to agree with WhyByFlier, disengage AP and fly a max attitude of 17.5deg Nose up, I'd also keep a good eye on the VSI to keep a positive ROC which is what you need and if you get to a full aft stick deflection then so be it.
I think this applies unless there is a logic in the Flight Envelope part of the FAC where the Windshear Warning would override the CLB engagement at Acceleration Altitude.
If such logic exists I don't know of it, but it would not surpise me if it is there.