1967 was a simpler time...
They thought it was harmless to have a young lad wrap his arms around a 30-year-old man and ride him.
If I were a more suspicious type, I might think that they'd named the young lad after the effeminate villain Joel Cairo from The Maltese Falcon, which would mean that maybe Filmation's writers and artists were in cahoots on slipping a little adult wink past the censors ("Take that, Dr. Fredric Wertham!").
Yet, even if I seem to split my time wincing and laughing at them, today (and perhaps this is pure nostalgia on my part), but I'd definately take the campy 60's action toons over the completely neutered 70's ones...(Well, at least until Challenge of the Super Friends gave us the Legion of Doom in 1978...)