Is the mckenzie method bad if you have facet joint injuries?

No: Unless you have an injury that has resulted in instability warranting surgery, the mckenzie method is an excellent program for most all with back or neck issues.

Yes: The mckenzie method frequently incorporates extension of the lumbar spine. If the lumbar facet joints are painful, this will exacerbate that pain and make it horribly uncomfortable. With that said, it may bear trying. It likely won't cause further harm though unless the joints are unstable.

Interesting Thought: Given that the Mckenzie method focuses in extension based exercises to help, it can potentially aggravate facet problems. I would discuss your concerns with yur therapist and see if an alternate solutions can be made regarding any pain you may perceive with tyne extension based exercises.