Welcome to the spin zone. As stated before, assessment and market value have very little in common, and the blowhole Larry Stone, who clearly has an agenda, is using his position to spin facts for the public. 44 million isn't a totally out of the question number for assets, but we all know that there's more value to the park than that. If Cedar Fair is leaving a profitable business behind, than they want to be paid to do so.
The 49ers are making a bid for the park to get it out of their way. Anyone who thinks they will actually pursue it as a business is kidding themselves. If the stadium is built there, than land values will go way up, and investors will be tapping on the shoulder of the city (or whoever owns the land) with a bag of money to develop around it (cough...Astroworld...cough). Cedar Fair would have traffic/parking problems, be landlocked, and probably have to deal with an NFL franchise (who usually think they are Gods gift to the city in the first place) in order to get anything done. I don't blame them for opposing the stadium. If they've done their homework and learned from the past, than they know that amusement parks next to stadiums have very little life expectancy.