Right mooring state but wrong residence state. At the time of purchase, Kerry was senior US Senator from (and obvious resident of) Massachusetts, a state frequently aliased as Taxachusetts.
It was that state's cost of ownership / taxes that drove the esteemed US Navy Vet to follow the common tax-avoidance strategy of keeping an asset away from the tax assessors & collectors! An amazing act of self-interest by a champion of larger government (driven by larger tax requirements!)