Omar Mateen "was not a stable person," his ex-wife told The Washington Post, which did not name her. "He beat me. He would just come home and start beating me up because the laundry wasn’t finished or something like that."
First, Mateen had no criminal record. IOW she didn't report him. I'm not criticizing, just putting her comment in perspective. She may have been entirely correct - about the beatings, about his stability - but it wasn't piblic record.
Second, if he did beat her, that is permitted per Surah 4:34 of the Qur'an.
As for the father's statement, he's not going to say here in the US in English that Islam was the motivation; he might even be smart enough not to say it in his native language while here in the US. But in Afghanistan, in Pashto or Dari ...