It is only reasonable to require a laptop if it is specified in the class or course requirements
It is not reasonable to expect students to have their own laptops unless this was specified at the time they signed up to the class or, alternatively, it is required for the course overall (or the course provides them). Otherwise you are springing an additional, and expensive, requirement on students who may not expect this.
Even then, this is a necessary condition not a sufficient one. You cannot avoid excluding students who cannot afford a laptop, for example, and you're requiring students to lug heavy equipment around with them for a single class.