Feel free to ignore, as I am interpreting this question more generally as "should we teach in college things that students should have learned earlier?, i.e. should prerequisites matter?"
My take: For most of my 40 year career as a college math professor, I proceeded somewhat as follows:
The prerequisites of my course are clearly stated, and I am obligated to teach what is on the published and departmentally adopted syllabus. Therefore if a student does not have those prerequisites, I have no obligation to cater (in class) to his/her lack of preparation, indeed I am obligated to the well prepared students to not do so. I am however available in office hours to tutor anyone wishing to compensate for this lack of preparation, free of charge, (and to do so as late as 8-9 o'clock at night, in spite of complications this caused at home).
Years passed, in which, as measured by the pre-class test for prerequisites, the percentage of enrolled students having more than 15% of them approached zero, and the number of students taking significant advantage of my free tutoring stalled at 2 or 3 total, literally over 20-30 years, and I realized I was orienting my class to almost none of the students who were in the room.
Thus I began to ease up considerably on my expectations, and to try to meet everyone where he/she came to me. I got much more effective at my job, and then was soon forced to retire.
That is why I am now here, where only those come who actually want help.
verbum sapienti.