Burning the remains just to make sure was the right thing to do. And he didn't burn the town down. It was still standing afterwards. That was a fucking demon general and if the Hero judges to burn it's ashes again and again, you accept that decision and don't complain! Though he could have warned them. Also right now goddess-chan is MC biggest cheat (celestial gate), but also biggest weak point (can't keep her trap shut).
I see why the Hero also wants the tools, but not the company. If his companions turn out to be as stupid and the townspeople and as meddlesome and always complaining as the goddess, he is better off without them, before the sabotage him in battle.