Maharaji's philosophy may well be primitive, but not for the reason you both cite, I think.

While in common English usage the 'heart' is, as you say, a person's emotional center, or limbic system even, Maharaji does not mean it this way. He means 'Heart' with an upper case 'H', rather like a person's soul - that part of them which is not 'mind' at all, but beyond it - a direct synonym for the Hindu 'atman'.

I personally would argue against even that, but at least there he is in agreement with most religions. That may also be primitive, but you cannot dismiss that usage without dismissing most religions (as I said, I personally would, but that is another topic).

The bit about it that is typical of Maharajism, is instead of using 'soul' or 'atman', in which at least he would be using a word with a commonly understood meaning, he takes a common word (heart), spells it with an upper case first letter (at least he talks that way, whether it is printed so or not) and leaves his atman-like meaning to sit on top of the common meaning of 'heart' as the emotional center.

He does exactly the same with other words - the most obvious example is 'knowledge', which has a clear common usage (my dictionary defines it as 'the psychological result of perception and learning and reasoning'), and he puts an upper case 'K' in front, and means by 'Knowledge' something quite different (four meditation techniques with his grace to make them work).