This seems to be the kind of slide made by someone without a lot of experience presenting work.
The other issue is, some people really, really, don't want to speculate.
In this case it seems that the person who made the slide probably assumed that the tile could be broken with a high enough probility. But because it was outside all available data, the slide says that we don't really know.
Of course, anybody in a position to make such a go-no-go decision should have enough experience talking to engineers, and seeing this effect in action to recognize the slide for what it is. It is really weird to conclude that based on absence of data, it is probably safe.
