Good read, but the abrupt end surprised me. It didn't dive deeper into the solution to evaluate whether it actually addressed the observed issue.
Also, isn't the accessibility of radio buttons for keyboard users something you simply learn? <Tab> isn't the panacea of getting around a web page with a keyboard. I think of <Tab> as navigating interactive elements by default, but within those elements the arrow keys allow more granularity. Several instances of that behavior, including radio buttons, shown here: https://webaim.org/techniques/keyboard/#testing
Also, isn't the accessibility of radio buttons for keyboard users something you simply learn? <Tab> isn't the panacea of getting around a web page with a keyboard. I think of <Tab> as navigating interactive elements by default, but within those elements the arrow keys allow more granularity. Several instances of that behavior, including radio buttons, shown here: https://webaim.org/techniques/keyboard/#testing