Star Trek has been pro-Alcohol and Anti other drugs from the beginning.
The "poisoned" fruit in the way to Eden was clearly a reference to the dnagers of increased use of all kinds of substances in the late 60s. Interestingly, Alcohol is depicted as something positive and part of everyday life. In every love scene, every social ritual, any shore leave scene, Alcohol plays an important part.
I think the interpretation of "way to Eden" is easily debated. Further, I think pot smoking Beatniks like myself may even have a further insight as to what that episode is about.
Well for one, there is no smoking reference, nor any drug reference. It seems to me that the episode is more clearly a statement of caution against the excess of the movement of the time, which at that point was peaking. If we are to infer an anti-drug reference, I think it is more clearly against the excessive use of LSD as "the answer", and perhaps the leader of the space hippies is a parallel of Dr. Timothy Leary. The "way to Eden" was a parallel for taking LSD, and the TOS writers nailed the pathos of that path on the head before the Hippy Movement had started to spoil. But it is worth noting that what spelled the end of that was not pot or LSD, but speed, heroin, even alcohol. And if one doesn't understand the enormous difference between a pot smoker who takes LSD a few times year, and a heroin fiend, that can see that these things are not even on the same continuum, well then that person, well meaning or not, is talking out their arse.