I always enjoy reading different opinions regarding eminent domain and the taking/compensation/use of land for different purposes.
While I personally believe this site should be preserved; I have no skin in this game. The path of least resistance for preservation IMHO is to let the land lease run its course and not renew it. That would give the state of Ohio 50 years to plan and set aside funds to properly preserve the site.
Lets put the shoe on individual feet: Lets say you personally owned a piece of land a third party determined had something of historic/environmental significance on it. You want to cut down a few trees, put an addition on the house or install a pool or detached garage on land you pay real estate tax on annually. Someone says to you that even though zoning law permits you to make this property improvement you can't do it at all; not even if you find a separate location on your property because of the left footed spotted nahwhal has habitat on you land or perhaps folklore states indigenous people had a sacred stone on site. Give this some thought.
I long ago recall meeting the woman who led the fight to save The Great Swamp in NJ from becoming an airport the size of JFK, as opposed to the mess we deal with flying in and out of Newark Liberty International. The case she made to save The Great Swamp was masterful PR mixed with just enough science to make her case and her group prevailed to kill the airport.
Her family had long owned a large tract of land in the Great Swamp watershed. She was getting on in years and wanted to break the property up into several building lots for estate planning purposes. As part of the subdivision process in NJ, environmental review and mapping of protected wetlands and their required buffer areas is mandatory. Given the "environmentally sensitive nature" of land in The Great Swamp 150 or 300' buffers around all wetlands was required by law. Through some networking and little science, the buffers were reduced to 50' allowing more building lots to be approved.
Rules are Rules, until you own the land and are impacted, then it's private property where the land owner knows best and wants what he/she determines to be the highest and best use.