Assuming there is a detected 51% attack, what would be done against this? Spinning up more nodes to counter attack is not an incentive for other "good" (whateve

Assuming there is a detected 51% attack, what would be done against this? Spinning up more nodes to counter attack is not an incentive for other "good" (whatever this means) miners because keeping unused mining capacity at hand is equal to losing money. Detection is worthless without applying counter measures.