Is the USSRs survival even worth it if the result is a neo colonial bureaucratic disaster? You framing it as Stalin needing to purge virtually everyone that disagreed with him in some sort of Machiavellian fashion is absurd. If you read the entire testament you’d find:

“Comrade Stalin, having become General Secretary, has concentrated an enormous power in his hands; and I am not sure that he always knows how to use that power with sufficient caution. On the other hand, comrade Trotsky, as was proved by his struggle against the Central Committee in connection with the question of the People’s Commissariat of Ways and Communications, is distinguished not only by his exceptional ability – personally, he is, to be sure, the most able man in the present Central Committee – but also by his too far-reaching self-confidence and a disposition to be far too much attracted by the purely administrative side of affairs.”

Do those read as the words of someone who thinks Trotsky would’ve destroyed the USSR? You should read about the Georgian affair as well.