Why should mind be free of thought? It has evolved to observe, think, act and remember.
In living form, things will always be in duality, multiplicity, even when one talks about animals or trees (male, female) - what constitutes us can very well be in an inanimate form, like what remains after cremation. But human mind can
understand non-duality (with analysis and science giving a hand). This
understanding is jnana, enlightenment, nirvana, moksha, deliverance or whatever one may like to term it. A mind with no thought and a mind in coma are no different. Mind cannot be without thought for more than a few moments.
BTW, Sankara said, "I do not need Moksha, because I am always free".
".. na dharmo na cha
artha na kamo na
moksha, .. Shvoham, Shvoham"
(.. I do not have any duty, nor money, nor desires nor moksha .. I am the aauspicious, I am the eternal)
Nirvana shatakam - Hindupedia, the Hindu Encyclopedia
Arumugam Chetiya here.