Elderly friend needs to move his very aggressive sister with dementia into skilled nursing, but is afraid. Any resources out there for this?

It's difficult for long term care facilities to manage a dementia patient that is very aggressive. I agree with BarbBrooklyn above getting her to a psychiatric evaluation. She may need to get medication adjusted to help her with her mental distress. Once, stable, they can determine what level of care she actually needs.

Why is he afraid of skilled nursing? If she needs that level of care, her doctor would indicate that. She may pay privately or be evaluated for Medicaid long term care benefits. If she needs AL or Memory Care, some states have benefits for those types of places as well. Normally, the state will have a website that describes the benefits. Also, check with counsel on aging or county dept of social services.

She should be evaluated by a geriatric psychiatrist; she is clearly agitated and meds may help.

This should be done before she moves, because if she's aggressive, she's not going to allowed to stay in a NH.

What kind of doctor is managing her care? Is she on any psych meds currently? Has her doctor been advised about the aggressive behavior?

In some areas, there are "senior behavioral units" which a geriatric psychiatric facilities where meds can be administered and evaluated for efficacy. You might want to look into if that is an option in her area.