Considering the Soviets treated the Cossacks like shit from the get go, I think they're willingness to collaborate can be understood.
The Soviets treated Cossacks the same way they treated all landowning classes with reactionary tendencies.
Cossacks elites owned disproportionate amount of land in areas traditionally settled by them with teeming multitudes of poor workers renting from them...but a lot of poor Cossacks did join the reds.
In any case, yes, the way of life was pretty thoroughly destroyed. But you have to consider if that way of life was even possible in a modern state from the outset. The fact that the destruction was violent was the only real (very real) issue.
Anyway...not Soviet apologia, just context for what the Cossacks were at the dawn of Revolution.