Presumably it won't be Trotsky leading Mexico, but a Mexican Trot, because otherwise they'd have to change too much of the Soviet events and tree.
I believe the only alteration needed would be to check on the Soviet event that brings Trotsky back which branch Mexico is going for, not firing if they are going commie.
I don't think he's going to be the leader anyway, but that's because I believe it would be too memey, having a Señor Hilter in a very obscure event might be fine, but having a whole branch of your FT like this is a little too much.
Trotsky could still be made a powerful minister though, and that would indeed not block anything from the Soviets, as if the event fires, one minister would simply become unavailable.