Every time Data plugged a fiber optic cable to his head to run a diagnostic, interface with the Borg or download a .dat file to B4 it was reinforced he was a machine.
He spent 7 seasons repeating like an automaton he wanted to develop emotions. Well, he didn't develop any: eventually a chip was installed and boing! emotions.
And, plausibly, he can be restored in B4's hardware. That plausibility is a point.
So does the fact that they were able to simply plug Spock's mind into a new body mean that Spock is a machine?
To my mind, Data is a sentient being. That makes it irrelevant to me whether his body is made up of living tissue or wires and circuits. Therefore, Data wasn't "destroyed". Data died.