In his words, it sounds all well and good that students have all the time they want to learn the materials. In practice though, you now have no way of gauging how well students are retaining the lessons until the end of the quarter. There's no way to actually catch them up, so the solution has been to drop testing standards as well.
Teachers themselves aren't complaining so much about it because it's a lot easier for them - less grading, less conflict with students, and they can stick to their planned curriculum without slowing down for students.
The "equity" piece of it is mostly window dressing - outside of some grading chicanery there is no reason to believe that it would do anything other than increase the disparity of outcomes between students later in life.