It could be, but the Wikipedia article notes that she may have also suffered a birth injury from hypoxia.

Rosemary's story is so tragic and heartbreaking. Her life was filled with what would today be considered multiple instances of medical malpractice, and heartless, unethical behavior on the part of the Kennedy family. Her father didn't even tell her mother about the lobotomy until after it was done.

Incredible that she lived to the age of 86. The nuns taking care of her might have actually cared, which could hardly be said of the Kennedy family.

Those are not unrelated. Both from my family and from looking at the research, there's a strong correlation between long/difficult births (sometimes explicitly hypoxia) and autism.