Assisted living is isolating father from family and will not let me visit. Is that elder abuse?

I see in your other question, you had indicated that your sister is DPOA and you are unhappy with her placing your father into AL. Family dynamics and situations are often complex so I’m sure there is much more to the story. If you are willing to share, it would help everyone offer fair judgment and solid advice.

I have heard of this - usually in the NH setting and never for an indefinite time period. Sometimes I know it depends on how long the person has been there and whether or not they are adjusting well to the facility. And, it's usually phrased as a "request" rather than an actual restriction on visiting. For some people, outside visitors can cause concerns/confusion/agitation - which persists long after the visitors have gone home. No matter the reason, someone at the facility should be able to explain it to you clearly and address all questions/concerns that you have about it.

All the Assisted Living Facilities I've ever seen have an open door policy. In other words, anyone can come visit any time they'd like; the resident can come and go as they please, etc. So your header here makes no sense. How can an ALF 'isolate' your father and prevent you from visiting? What are they doing, locking him inside his room and standing guard to make sure you don't go inside????

I don’t know why you would be isolated. Have you spoken to them directly about your concerns? What’s going on with your dad? There has to be a reason for this. Please give more details.