disable fixed strike table optimizations

src/main/java/gov/usgs/earthquake/nshmp/model/GridSourceSet.java

@@ -105,7 +105,7 @@ public class GridSourceSet extends AbstractSourceSet<PointSource> {
      */
     // System.out.println(Δm);
     // this.optimizable = (sourceType() != FIXED_STRIKE) && !Double.isNaN(Δm);
-    this.optimizable = this.magMaster.isPresent();
+    this.optimizable = (sourceType() != FIXED_STRIKE) && this.magMaster.isPresent();
 
     // System.out.println(Arrays.toString(magMaster.orElseThrow()));