Now that part I agree with. The problem is she's 22 now. Umar has had 4 years of access to her without the mom if he wanted to.
Exactly.
Also, even if you're skeptical about receiving a text from your estranged daughter due to not recognizing the number it doesn't explain or justify treating her like she's some stranger.
He still could have simply just called the number and confirmed it was her or told her to call him no matter what number she was calling from.