You are right, I have just checked the code and OpenAccess is indeed not generating log files when the model is configured for medium trust environment. Normally in medium trust scenarios the application does not have access to the file system, although it should be able to create files in its application directory.
Is this your case - do you want to create log files in the local directory of the application? If yes, we might need to reconsider the current approach and enable the logging in some cases.
the Telerik team