Since I am writing in english, I would say that this website would be mostly aimed at english speaking peoples in america and elsewhere, but the Juno-6 was a product you could purchase in a variety of places in the world. So in that sense, it would be for anyone with interested in the keyboard with the capacity to read or translate this webpage.
The "Juno sound" is a mainstay in 80s style music, which has seen a resurgence in the culture as of late. Even though in practice the age of the person who would be into these old keyboards would be 50+, the bar of entry is actually lower and should be considered teenagers and up.
That doesn't play into this I don't think.... Both men and women can and have apprecitated musical instruments, let alone electronic ones.
Goes without saying that this information mostly pertains to musicians and hobbiests who own these keyboards, but documents like this can appeal to people who don't own them yet, or people just interested in synthesizers in a passive sense, or just for entertainment purposes.