They shouldn’t have to pay the money to leave.
Agreed. But the law in Texas isn’t settled - a local Episcopal church paid about $1.2 million to leave (and affirmation of sole responsibility for debt of $6.8 million) in 2006 with the facts substantially similar, except the Episcopal church property wasn’t nearly as valuable as the Highland Park property. (Annual giving at the Episcopal church was about $3.8 million at the time, Highland Park is about $8 million a year.)
The biggest problem, as I saw it, for Highland Park is that they did have a vote on pulling out with their property during a window when that was allowed, and a majority of about 43% carried the day to stay with the denomination. So it isn’t like they stumbled into the situation.