Matt,
sounds to me like you'd rather blame Angloesque for setting a specific disciplinary action. I presume that it was made clear to the students before papers were assigned that "Plagiarism = F". That is a simple, easy-to-understand, well-stated punishment for plagiarism.
I don't know if "Plagiarism on Paper X = F on X" or "Plagiarism on any paper = F for course". The first should be more to your liking, since it offers the possibility that one's grades on other papers may carry them successfully through the course. The fact that for this student, "F = violates academic conditions for continued enrollment" is unfortunate, to be sure. However, laying out consequences for plagiarism, and then carrying through on the consequences, does teach an important lesson: actions have consequences. And that sounds like a lesson this student was (and may still be) in need of learning.
It's clear from the tone of her post that Angloesque did not want to cause the student's expulsion, and that it was an undesirable side effect of assigning the failing grade. You need to get off your own high horse; there's a clear difference between making a mistake and getting caught cheating.