Your arguments aren’t sound. As an academic, it should be easy enough for you to see the problems with your arguments. Universities are places with people not institutions that focus solely on productivity, progress, and “financial sustainability”. The constant rhetoric that universities are under corporation-style peril from their shareholders is beyond far fetched. What you’re saying is that you won’t directly and illegally attack unionized workers who can fight back but you will slowly erode the bargaining unit and contract out work to those who cannot fight back. You say so yourself, quite directly, in your email. It is your plan to contract out these positions.
You’re attempting to continue to reduce the quality of rights for workers on campus. As workers retire or as you put it “freely vacate” will you commit to replacing them with unionized workers or will you continue to contract out those positions? No, you won’t. And productivity cannot be the model for a university if that means that you eliminate good jobs and contract out jobs to avoid providing good working conditions and benefits. Contracting out also means contracting our your responsibility to the people who work for and serve the university community. There’s only one responsible option here: stop trying to erode bargaining unit work.