The scientific basis for decommissioning is the continually decreasing hazard from any plant doing it. As the hazard decreases, the size of the Emergency Planning Zone can shrink.
At any time, the potential hazard comes from the radioactive atom splitting products. In operation, there is a steady, large amount of radioactive products. Once operation stops, the amount of radioactive products decreases continually.
The radioactivity creates heat in the fuel and surroundings, enough to require water cooling for five years. After five years, the heat from radioactive waste has reduced enough so that they can continue air-cooling in dry casks.
Economics? The writer forgot to mention that in the first year of the extended license (March 2012–March 2013), Vermont Yankee made so much money that Entergy paid the state almost $17 million, per the purchase agreement. Promise kept! Entergy decided to give up on the plant because there is no guarantee that natural gas prices will go back up any time soon.
Yucca Mountain is the place for used fuel, per a law passed by Congress and signed by the president. This president and the former Senate majority leader have been breaking the law by not continuing the development. The new Congress is funding completion.
So 51 towns voted against VY? That's out of 246 towns and five unincorporated areas. Most towns in the state either voted for Vermont Yankee by voting no on such questions, or there was so little support that the question could not get on the ballot.