The idea isn't that bad at all and many of the themes are fitting for TOS.
A disillusioned group, people seeking harmony with nature, disaffected outcasts turning their backs on technological conventions and authority, the common TOS idea of finding a paradise... these could be worked into a very Trekkian story.
That they used an obvious analog of '60s hippies was perhaps too on-the-nose, especially dating it.
TOS has used stand-ins for Communists and Soviets and Vietnam and other modern-day institutions with success.
I wonder if "Eden" would have worked better if the story characters weren't so blatantly space hippies. If their ideas and purpose were similar, but maybe portrayed as something less obvious.