Yeah man, it does suck. I do wish I'd had more time with both my parents, they both died really early in their 50s, I don't think you can ever have "enough" time.
I wish my mother had been given the option in her early 50s, the number of people punished by authoritarian governments that deny self determinism and force people to be put through experiences literally worse than torture is mind boggling, I cannot fathom it.
I don't think anyone who has seen it even a single time can honestly make slippery slope arguments, I have to assume it's ignorance and that these people are simply "actually" nerds doing recreational theory crafting. I assume it's the same headspace as flat earthers, it doesn't effect me so why should I care about aligning my thoughts with the real world, let me invent theoretical overlords and victims and argue about this new synthetic world that exists in my imagination.
I just can't be uncharitable enough to believe a person who has seen it first hand, that a person would embrace such unfettered cruelty as to deny a person living in constant hell a drop of water.
That being said... fuck, back in 2000 I did meet a bunch of people that denied hiv existed and said even if it did it was a punishment on gay people and it would be better if it wasn't cured so they would be scared and "behave" (yes, I personally met these people, the non-existence was rare but the "shouldn't develop treatment" was not a minority view in the city I lived in at the time.)
After my mother died, for a while I volunteered with "No one dies alone.", I doubt a single person who has done so for any length of time is going to argue "slippery slope".