Ah, the Karma Gods were in fact enjoying my plight and had one more twist for me. After I had thrown up my hands and said out loud 'I give up', I put my right hand back on the mouse to click the cancel button that, having finally came to terms with, would never turn into an 'OK' button no matter how much I wished for it to happen.
A dialog box popped up saying (and I should've taken the picture) 'The installer will finish installing the current package and then exit'. Great!, I thought, that's just what I want! It's on the last package so this magical backdoor has provided for me.
Er... not quite:
Notice it's still on step 14-- still the very last step. Only now the cancel button is greyed out, as is the 'Exit Window' button at the upper right.
I wonder what will happen if I try to kill the process? Dare I?