A bill that requires manufacturers to offer phones that have this feature and phones that don't have this feature I could see as being okay, but to require all phones to have it and leave the user no choice (fwiw, being able to disable it after purchase is a false choice) is ridiculous.

Kill switches are never the right choice to solve this. Once this technology exists and is widespread (as the article points out, manufacturers are unlikely to maintain two models, with and without this unless legally required), what stops oppressive countries from using this feature from disabling the phones of people legitimately protesting like those in the Ukraine right now?