Revoke it retroactively? Holy crap people. HenryAlan was along the lines of the right analogy.
Shirley's letter was filled with conjecture and examples of other projects that have no bearing on the finances of this property.
There is a big difference between "could Libery Mutual have paid for the tower without a tax break" and "would Liberty Mutual have paid for the tower without a tax break". Think about it this way, Fidelity is shriking in Mass and growing in NH, NC and Texas, because guess what? It costs less to be there.
Insurance companies pass along costs to customers. When you are competing against competitors in lower cost places (think Hartford, Columbus, GA, Columbus, OH, suburban Chicago, etc) it's hard to have lower business costs when operating in Boston's Back Bay. Sure, you probably can recruit brighter people that helps drive revenue/reduce expenses, but those people and that location costs far more.
For $50MM in savings, I can think of lots of sunbelt states that would happily have office space and lower labor costs that would have soaked up those jobs (not to mention they would have offered incentives too)
In other words, I can afford a new Hugo Boss suit, but I personally don't buy them until they go on sale.