This is a different concept from isolated muscle activation.
There are many such techniques out there and MAT in the US is not new – but the principle is the same – which is why I say stretching the Hip Flexors and competing muscle groups is probably going to do more good than trying to ‘activate’ a muscle that is in ‘in competition’ with hyper active groups. It is very rare (if even possible) in my experience that a muscle does not deactivates when needed in healthy individuals.
Also bear in mind that what may work for a chronic case does not nor should always translate into ‘prehab’