Exactly. I've implemented a xorshift-based rng inverter previously, and here's the implementation for the algorithm in the article:
https://github.com/m1el/samaras/blob/master/src/xorshift128....
https://github.com/m1el/samaras/blob/master/src/xorshift128....
It is about not knowing the internal state but figuring it out after having 2 (or 3) consecutive outputs of the random number generator.