When you floor a Tesla you get every ounce of acceleration right off the bat because electric motors produce all their available torque virtually instantly. That's a big bonus when you're towing something in the neighborhood of 4,000lbs.
The inverse is true with the Alfa. I've driven it; it's fun as hell, but it's not really about acceleration. Its turbocharger is peaky, meaning if you simply floor it from a standstill, it takes a fraction of a second before it's really got full power. In this case, that fraction of a second gives Tesla the advantage.
Wanna know what the best part is? The 4C is an incredibly fun car, and the Model X is an incredibly quick crossover, so everyone wins. Well, unless you were driving the red 4C. Then you most definitely lost. Good show, Tesla.