First of all, Q has nothing to do with decisions on criminal prosecutions (that is the DOJ's job) or military actions(decided in the Pentagon)
But if you really want to know why the Trump administration allows Soros to continue, this is something Q told us a long time ago.
The policy is BOTTOM TO TOP
Because if you cut off the head of a Hydra then the body will sprout 10 new heads. It will take a while for those heads to compete for dominance and for you to learn where the real power/threat lies.
Arresting Soros would be stupid because he is like a head of the Hydra
Instead, we are taking down their organization piece by piece, removing the sources of power and support, destroying their weapons and their fighters. When they have no ability to attack any more, then we cut off the heads.
In the meantime, their minions are feeling the pain, and they can do nothing because our strikes come without warning. We have spies inside their organization. We know what they are planning. They can shout and scream but that is all, because their resources are being blocked, or cut off.