If I dare to interpret the two examples that you brought up (in reality, there are more such examples, such as the Baltic states), they all demonstrated what I have said. In the same way as the purge, the collaborators and the cause of them weakened USSR, but because of their insignificant numbers (even in Ukraine with a large population, the collaborators are mostly from the west, the east identified themselves more as Russian), they didn't make a meaningful unti-faction within USSR. Their effect is similar to the unti-Hitler Wehrmacht officers, just a bit bigger in numbers. One example is that Khrushchev, an Ukrainian was crucial in maintaining the USSR control on Ukraine and latter succeeded Stalin (a Georgian some of whose ethnical brothers also collaborated with Germany). The core of the issue is that within USSR there was no organized and unified political/ethnical faction that wanted a German win except some unorganized people who assisted Germany out of their resentment to USSR (some of their grievance are surely justified). However, without a clear vision those collaboration with the Nazi simply won't make any difference.