non-toxic Rick seems to care about everyone generally. He felt a moral obligation to care even for his discarded toxins, to the extent that he walked into a near-deathtrap (only to be saved at the last second by sea-cucumber lady).

Yes. Thanks for saving me from having to point that out. The machine doesn’t remove toxins, it removes what each subject *thinks* are their toxins. Rick thinks he’s held back by his affection for Morty, which is why toxic Rick cared about saving toxic Morty. This was a major plot point, and literally explained by…