That is untrue. At the time of the Founders they called it "Mahometism", but they were interested in protecting ALL religions, including Islam.
In a sense, but what I meant was, their primary concern was with Protestantism and Catholicism, and in that context their interpretation of "Mohametism" was in terms of 18th-century comparative religious theory, which subscribed to the theory that the ethical principles of Judeo-Christianity as summed up in the Ten Commandments and Golden Rule were expressions of natural law essentially similar to those of all other major religions. In extending protection to Mohametism they weren't conceiving of it as something radically at odds with Judeo-Christian ethics but as something falling under the paradigmatic umbrella represented by the Ten Commandments and Sermon on the Mount. This regards more of an Enlightenment interpretation of Islam than Islam per se in its own right.