Id bring the kinetic chain into this question.
Injuring one part of the chain hurts others. Knee dysfunction will often lead to ankle and hip problems.
The hamstring will be especially important to ACL injuries, because it is on the opposite side of the body and may be used as an antagonist.
Activating that part of the body means that the ACL could be stimulated to stretch and shorten, but use the hamstring to lead it.
It is important to strengthen all of the muscles of both legs for these clients. And all clients. ACL repair usually involves using a portion of healthy ligament/tendon from another location and replacing the damaged ACL with this tissue. The outcome is dependent on many factors. The only controllable factor is the effort of the patient to rehabilitate properly. So much depends on the consistency of the patient to stick with their rehabilitation program that I would say after the skill of their surgeon and the pre-surgery condition of their fitness, the patient’s commitment to rehabilitation is the most important part of recovery.