That does not make it right. Simply because Islam has leeched into their vocabulary, does not preclude them being corrected.
By the way, the usual Hebrew word for God, "Elohim," is cognate to the Arabic "Ilah". Everyone agrees that "Allah" is a contraction of "Al Ilah".
In other words, "Allah" is a lot closer to the Hebrew word used in the Scriptures than "God" is.