Okay, I misremembered something, for God did bless Ishmael. That said, the covenant is still with Issac, not Ishmael. And that does not make YWHW the same as Allah.The Torah does Not say that God rejected Ishmael.
In fact, it says the God blessed Ishmael and made him the Father of a great nation.
As Muslims believe that the God they are worshipping is the God of Abraham, and the God of Abraham is the God of the Christians, then yes, technically, they are one and the same.
It is a deception to make them bow to the black rock in Mecca.