You’re 100% right. That was the beginning of the mind control. I have no idea who called television the “boob tube”, but it wasn’t nicknamed that because of all the topless women on it.
The feeling that TV was a mindless activity for the mindless masses was captured in its cheeky new sobriquet, the boob tube. Boob, according to the Oxford English Dictionary, then commonly referred to “a stupid, inept, or blundering person; a fool.” In other words, boobs were happy to sit in front of the TV set and fill their brains with a ceaseless procession of low-brow content. Some people did defend the device, praising its ability to educate and engage viewers.
https://www.mentalfloss.com/article/641152/why-is-television-called-boob-tube