It makes sense if you look at it as a correlation, not as causation. The point is that one cause (less review of experimental kernel features), which is known to underlie the "this crashes" problem, can also potentially cause the "it could have back-doors" problem.

Of course, as you say, not-crashing back-doors can make it into releases, too. Open source's generic promise that more eyes will make bugs shallow is not a guarantee.