Facial physiotherapy after facelift?

Agree with other consultants that facial physiotherapy is unlikely to damage the results of your facelift because at 90d,  your wound healing is approaching completion.  As most facelift procedures don't depend exclusively on redraping and tightening skin, alone, the deeper repair work on the SMAS, which most of us do, will provide the results as well as resist any external deformative forces applied. Many surgeons actually recommend lymphatic drainage immediately post-op, which is a lighter variation of the treatments you are receiving.  

this far out you should be fine.  most of the healing occurs within the first month.  sometimes when necks are "too tight" I actually recommend stretching exercises.  shouldn't be a problem.