A palpable fear in Wisconsin is access to water. Another is the potential abuse of eminent domain.
When Foxconn made a deal with the state to build a factory for large screen TVs, water was a major part of the deal. They were given an exemption on obeying state environmental laws. They also condemned farms and properties in order to buy the land from owners who didn't want to sell it.
A potential further reason for secrecy is that water use in the Great Lakes watershed is governed by a treaty with Canada, and the people in the Great Lakes region are quite united on being protective of our water even when we disagree on a lot of other political issues.