The government has no more and no less "moral authority" to impose tariffs than any other type of tax. If the government can tax income or consumption, it can impose import duties. In fact, import duties accounted for most of Federal Revenue in the 1800's, when there were no income or corporate taxes.
>> import duties accounted for most of Federal Revenue in the 1800’s, when there were no income or corporate taxes <<
Of course. But “tariffs for revenue” were understood during the 1800’s to be conceptually and morally different from “tariffs for protection.”
Tariffs for protection are morally indefensible, while tariffs for revenue are a legitimate (if not always efficient) government tool.