Saved in the Merit of Peace:

This is also seen from Rashi (Bereishis 11:9) who explains that the dor haflagah were not destroyed from the world, whereas the people of the dor hamabul were. The difference between them, says Rashi, is that the dor hamabul stole from each other and did not live in peace, whereas the dor haflagah treated each other with respect and friendship. This teaches us that machlokes is worse than theft and we see that the reason the dor haflagah was saved in the merit of getting along.