I think this is a great idea — to at least give the course builder the option of offering a free trial. If they don't want it, like Jason mentions, they can ignore it.

In my opinion a free trial to a course is not good or necessary. I like the way it is done on udemy. There are ratings and access to free lessons that are chosen by the instructor. If the course has no rating then in the beginning you could offer the course at a deeply discounted price using coupons, or an introductory price.

This would be excellent, give an access with an expiration date, a free trial for a membership, or to access the course for a couple of hours, it is very good to offer a free trial,