Special rules apply when you're teaching theology. There is room for theological exploration in areas where doctrine has not yet been defined. But ultimately there must be boundaries that can't be crossed. And a church has the right to set those boundaries.
"Academic freedom" is getting to be a tiresome refrain and tedious defense for theological shenanigans.
"Academic freedom" also means the freedom of the academy to fulfill its missions, and to teach the doctrines it was set up to impart. The largest and most conservative protestant denomination in the US, the Northern Presbyterian Church, was hijacked by the perveyors of an alien faith because they were too dainty to defend themselves, to hold heresy trials.