You have zero proof & did zero research on this person, yet trying to put someone who down sees profound benefit with the good old: "it's just placebo".
Just because there is no direct studies backing it up yet doesn't mean there isn't real effect. Could be keto, could be lack of certain starches or other foods, could be the focus & rhytm, whatever it is let's not discourage someone who is having a great practical benefit.
In this case there is literature & studies on epilepsy and keto, and OP was on put on epileptic medicine & describes a link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6361831/