SKU 206304 for an M&P9C with thumb safety

The usefulness of a mag disconnect is dubious. It's another part that can fail. The thumb safety is the most you would need.

In a tussle, you're more likely to release your magazine on accident than in a super-aware state of "Gee, about to lose control of my gun, better drop the mag to render it useless by the assailant". You want your gun to still shoot after you accidentally drop that mag.