Signs of adult possibly abusing adult daughter

Six years ago I met a biological son I didn't know existed from a short relationship I had 51 years ago in another country. He was adopted as an infant and grew up in the US. I'll call him Joe. He lives in another state and I went there to meet him. It was a very awkward visit with much strange behavior on Joe's part over my 3-day visit. He married young and divorced and has 2 adult daughters. The younger daughter has borderline personality disorder; the other is a lawyer (I verified this) I met his younger daughter, now in her late 20s and she is clearly on the spectrum. She also had twin sons from a sometimes violent past boyfriend. Joe told me his lawyer daughter hasn't spoken to him in years but offered no explanation of why and I didn't ask. The last conversation we had the day I returned home we were talking about football and out of the blue without me asking he said "my older daughter accused me of molesting my younger daughter, can you believe that?" I just said wow and that ended the conversation. He was answering a question I didn't ask. He said he would give me a call when I left. Months went by and he never called. I was happy to not get involved. There were many other red flags before, during and after my visit I won't go into to keep this short. Months later he started sending late night, I suspect alcohol fueled texts venting about how unfair his life has been which I didn't respond to. I'd sent him info a few years ago on how he could see if his biological mother was still alive via DNA. The last text he sent 2 years ago was chastising me for having unprotected sex with his biological mother when I was 19 years old. I then blocked him.

Am I justified in believing he may have abused his daughter?