Sorry, but that is wrong. You absolutely need to keep the concrete warm, especially curing during winter months, when temperatures drop below zero. When pouring they often tent or provide heat-blankets to maintain and heat the concrete to prevent freezing. Sub-zero temperatures can cause freezing in the concrete, if left exposed, which is detrimental - causing cracking, heaving and other issues, not to mention a slab that unsafe.
Your comment could also just be trolling...so shame on me, I suppose.