I don't believe that you are dealing with Marek's...but, the thing with Marek's is the bird is not paralyzed as we think of paralysis. They can continue to use the effected limb/limbs for a very long time but, the limp is the first thing that happens. Then, it gets worse and they cannot use the limb at all. They are permanently down.
Silkies skulls are open, especially in the vaulted variety. They really don't feel any different but, the opening is there. This is the same with all the crested breeds. Yes, he can hurt her by grabbing her by the head.
I'm really hoping that your little chick has gotten injured and with time will make a full recovery. It is important to keep her out of harms way until she has time to heal.