Why is the model matrix rotated around Z in ofxAssimpModelLoader::updateModelMatrix()?

Question is referring to line 497 in ofxAssimpModelLoader.cpp:

void ofxAssimpModelLoader::updateModelMatrix() {
    modelMatrix.glRotate(180, 0, 0, 1); // <----------- this line
    if(normalizeScale) {
        modelMatrix.glScale(normalizedScale , normalizedScale, normalizedScale);
    for(int i = 0; i < (int)rotAngle.size(); i++){ // @julapy - not sure why rotAngle isn't a ofVec4f.
        modelMatrix.glRotate(rotAngle[i], rotAxis[i].x, rotAxis[i].y, rotAxis[i].z);
    modelMatrix.glScale(scale.x, scale.y, scale.z);

If I comment out line 497, getSceneMin(), getSceneMax(), and getSceneCenter() return values that correspond to the onscreen model location/dimensions.

Otherwise those values are rotated 180 around Z compared to the model.

model and calculated bounding box

after removing line 497 vs. before