This would make sense. Cos why would she not correct Mohammad? There’s another thing that could contribute to Mary being called part of the Trinity, but is Mary in the Trinity in the Koran or the Hadith?
If it’s in the Koran, I’ve read that the Koran you can hop online and read was codified 150 years after Mohammad’s death vs the 30 years after Christs death to the gospel of Mark or the 10 years after Christs death to Paul’s letters. A lot happened between the 620s and the late 700s. Abbasids could have had an agenda in laying out their final copy of the Koran. The Ummayads and Rashadoons were already long gone by the time the Koran we have today was codified.