I read that site as suggesting complementary aids rather than substitutes.
I am epileptic and AFAIK it is very unusual for an epileptic to get rid of seizures without drugs. I need my meds. However certain things do help and have actually been supported by doctors (plural). For example magnesium. I have read that taurine has apparently reduced seizures in some people. I take it for anxiety and other issues resulting from sleeping problems. I have also read that GABA has shown positive results with epilepsy -although there is the issue about crossing the brain barrier. I agree with you that quackery as an answer to epilepsy is dangerous, but with epilepsy and interelated compounding issues nutrition awareness can help if it is informed by research, which it can be.
IDK anything about GABA, but some of the MDs here recommend taurine and magnesium for epilepsy in addition to the meds. They are pretty good with suggesting non-harmful supplements to assist in controlling seizures, because the meds aren't a guarantee.
One of the clients I work with has epilepsy, another two have Parkinson's. They have minor shakes in the morning before the meds take effect. I make a point of avoiding sudden temperature changes, i.e., cold floor tiles, and sometimes grip the extremities firmly but gently with a downward stroking motion. This usually eliminates, or at least minimises, the shakes. I am not sure if the effect is psychological or physical, because it is comforting to the client so keeps anxiety to a minimum, but it does help. Others who do not do this have not been as successful with controlling the clients' shakes. Just my two cents, maybe you'll find it helpful.