The "ableist" comment by the author seems a direct response to "I don't care about this because I'm not an epileptic", which is the definition of ableism: not caring about the disabilities of others. He/she seems upset that some animé purists only cared about watching the original sequence and disregarding potential harm to others.
Unlike with PB&J, where if you are allergic to peanuts you're not harmed by someone else enjoying them, exposure to epilepsy-inducing animé can maybe harm you if you glance at what someone else is watching. Say you enter a friend's house, and they are watching this episode, and they've already skipped past the warning (because, after all, it doesn't affect them) and you watch what they are watching and it turns out you are affected.
Of course, you cannot cover all risks all the time, but editing these animés just in case seems like a reasonable and safe choice to me.
And let's not be dramatic, everyone can still watch the animé, it's just that some visual effects have been edited to make them less potentially harmful. It's not like censorship.