You have built the model and the script works fine. These added lines are just some finishing touches that add to the script to make it work cleaner. You can delete the highlighted curves and zoom in on the Block so it fills all the rhino viewports. In scripts that build models, I almost always end the script with the zoom extants all command. This way the script ends with only your model fitting perfectly in every viewport. IO always end the script with Enter this way Rhino knows for sure the script is ended.
Add these lines to the commandscript:
Your script should now read:
Test the command script by highlighting and copying the text from Notepad, activate top view and click the commandpaste icon. This should create the manifold block delete the curves and zoom all viewports on the created model.
Press the F2 key and bring up the command history notice how the script answers the prompts that Rhino is asking. Quick shade the model.