Very low $\left|\frac{V_{\mathrm{ub}}}{V_{\mathrm{cb}}}\right|$ in Ma's $S_3\times Z_3$ model for the quark mass matrices

I show that a model for the quark mass matrices recently put forward by Ma predicts very small values for $\left|\frac{V_{\mathrm{ub}}}{V_{\mathrm{cb}}}\right|$ and for $\frac{m_s}{m_d}$. The first quantity cannot exceed 0.09, and the second one cannot exceed 18.3. Moreover, the smallness of the two quantities is correlated: if we want $\left|\frac{V_{\mathrm{ub}}}{V_{\mathrm{cb}}}\right|$ not to be so small, we have to accept a smaller $\frac{m_s}{m_d}$, and vice versa.