Maesumi's measure-zero conjecture for reducible and defective matrix families

Let $\mathcal B$ be the space of bounded families of matrices, $\mathcal R$ the subset of reducible families, and $\mathcal D\subsetneq\mathcal R$ the subset of defective families. Maesumi's conjecture. Reducible matrix sets have measure zero in the corresponding space of matrices, and defective matrix sets have measure zero within the set of reducible matrices. This conjecture concerns the size of exceptional families in the joint spectral-radius setting; the source gives no resolution status.