My opinion is that the safety of a building, whether it be from a fire point of view or a structural point of view, is a design issue, a performance issue. This is why codes are moving towards the performance-based approach.
There's no doubt that the integrity of a mass timber structure in a fire is extremely high, much higher than it would be in a steel building should the steel be left exposed, for example, because mass timber protects itself by developing a charring layer. In addition, a building that is built entirely of mass timber panels, which are airtight—and this is the case for CLT—will contain a fire and keep it from propagating throughout the building.
When you look at it from a performance point of view, I think it can be demonstrated that a timber building will perform as well as a steel or a concrete building if properly designed. There's no doubt about it.