I think Khrushchev was more an "empire holder" than an "empire builder". The Cuban régime did not originate as part of any Soviet imperial initiative, but once it was there, K supported it, within the limits of reason.
I also think K was sincerely trying to humanise and reform Soviet communism. Unlike his successors, he appears to have believed in it as a valid ideology. But it proved to be unreformable, and when a much later leader appeared who was resolved to reform it, no matter what, it simply fell to pieces in his hands. Never has a mighty empire collapsed with so little fuss. There is nothing as flimsy as a false ideology, once the falseness becomes generally known and admitted! Just like the Emperor's New Clothes, is simply vanishes as if it has never been, for in an important sense, it never really was.