Actually, official ICE release states that "Nonimmigrant F-1 students attending schools adopting a hybrid model—that is, a mixture of online and in person classes—will be allowed to take more than one class or three credit hours online. These schools must certify to SEVP, through the Form I-20, “Certificate of Eligibility for Nonimmigrant Student Status,” certifying that the program is not entirely online, that the student is not taking an entirely online course load this semester, and that the student is taking the minimum number of online classes required to make normal progress in their degree program."
So my understanding is that as long as their whole course load isn't online, students can take more than one online course, but only ones that don't have an in-person option.