If you actually read through the chart, you’ll recognize that there’s not a heavy “left-wing bias” - e.g. “democrats” are less protected than “rightists” and “right-wingers”; meanwhile “liberals”, “leftists”, “right-wing people”, and “evangelicals” all rank around the same.

Overall, the model clearly goes further to protect innate characteristics - especially those most commonly targeted by hateful rhetoric (disabled people, Black people, gays and transgender people).