I don't know about other languages on this but in English media or medium also has the sense of what environment someone or something is in. "What's your medium" "I use oils" etc. I suppose that it comes from the Latin, but can't find that dictionary at this time. I can find the Esperanto English dictionary which says that medio means "Sphere of (action, life) environment, social circumstances, habitat (surroundings)" etc. I don't know if this helps, but I really don't think that it's such a stretch to make the connection as one may think.
/redakto: ŝajnas, ke en la Rusa, pola, ĉeĥa kaj bulgara estas parenca vorto.
In french the word "milieu" can mean environment. For example, you could say "les salamandres vivent dans des milieux humides" which means "salamanders live in humid environments" or, in esperanto I guess "salamandroj livas en humidajn mediojn".
It still seems like a bit of a stretch, though. It would make more sense to me if Esperanto used a compound word for the sense of the word used here, such as "naturmedio" Just a thought.
It should, according to the Comprehensive English to Esperanto Dictionary: Milieu = medio.
I would report this should it ever come up again.
Both “environment” and “medio” are more general than the “natural environment” we are talking about here (suggested by “protektu”), and which can, more precisely, be called “vivmedio” in Esperanto.