Actually, there are Laws Against Forcing one to take medications. Except when Court Ordered. But, honestly, the Epilepsy Bill of Rights Claims we have the Rite to Refuse any medications/treatments.

My Sis did for over 50 yrs. Severe depression is what made her confess to DR her seizure status. She still remains Med free. She is on a Diet prescribed for people w/ seizure disorders.
Unfortunately, we Are Healthy Individuals. So, denial is Easy. If he is Stubborn, then I doubt you would convince him to seek Support from others' w/ Epilepsy.

Or counseling from a Therapist.
Our brains misfire at inappropriate times.

He will regret his decision if/when he wakes up to the fact the seizures haven't gone away & hopefully, he will not harm himself or others.

Have you considered videoing him during an 'episode'.? Make him watch it! How long has he been off his meds? Did a Dr wean him off, properly.
Despite his refusal to take meds, he still needs your support. The best way to do that is to Treat Him Normal! You may not be intentionally trying to 'stress' him, but, being 'pushy' will do that to us 'stubborn' old folks'

I know you are very concerned for your Dad, so, continue to talk w/ us. Vent All You Want!

Hugs! BTW: Do you Avoid 'caretaker burnout'?
Love Candi