Plenty of other Soviet politicians of the time (Bukharin, Zinoviev, Kamenev, etc.) would have done away with him too. This is a man who was basically the closest thing to Lenin's favored successor (and had even spent time during the last years of Lenin's life acting as his voice and delivering speeches for him and such). He blew it badly IOTL, and it's really hard to see him not doing it even with different circumstances.
Great minds...
Heh, always good to reach the same conclusion desperately. It's validating!
There is however another way one could get Trotsky into power. He did have power over the red army and he might have had the capacity to pull off a coup. Some of his supporters definitely did urge him to try a coup OTL. If he gets fed up with petty party politics and starts seeing the writing on the wall, he may try to pull something.
I don't think the above is likely given what we know of trotsky, but it does seem somewhat possible.
The Red Army experienced a degree of political oversight and indoctrination that made it unlikely for it to present an organized front to launch a coup. Attempts to organize a coup by Trotsky would either result in him being denounced by the army and shot, or the plot would be discovered and those involved would be shot. A military coup was something the party feared the most, and it worked to crush any possibility of it occurring.