Those of us who believe in sola scriptura fall into two broad camps (at least!) Some, such as Baptists, are more radical (striking at the “root”); others are more “group oriented.”
In a scenario such as you described, the radicals would declare the heretic to have departed from the plain teaching of Scripture. In other words, their interpretation is really no interpretation at all–it’s just reading the Bible. So the heretic would get the boot.
The less radical among us believe that the interpretation of Scripture is a group project. “If you leave a man alone with his Bible, you will produce a heretic” (Bill Ury). So the weird interpretation would be submitted to the judgment of history. Since history has been around for a long time already, we can pretty well tell ahead of the fact where this heresy trial is going to wind up The New Testament instructs the pastor to maintain doctrinal purity within his flock (Titus 1:13).
But history is uneven, so variations in belief will persist. At the regional or annual meetings of the Evangelical Theological Society, there might be scholars from 50 or 100 different denominations (I’m guessing here), but we all agree on the basics. (Well, there’s a few flakes floating loose, but they’re anomalies.)
Since we now abjure the use of force, sola scriptura means that only the Bible can bind the conscience. But “the Bible knows nothing of solitary religion” (John Wesley), so the Bible doesn’t give an individual the liberty to dream up and teach screwball doctrines within the church. He will be excommunicated, and he and God can work it out between them.
In sum, the individual answers to God, but so does the church and pastor. When agreement is impossible, the church must exclude the heretic. :bible1: