Having reverted to High Sierra after trying out Mojave with the previous version of 3Dconnexion, I vowed to be more stoical and wait until someone had reported that they actually had it working in 10.14. After reading your post and wondering if you had possibly confused the Terminal with the Preferences Pane > Security & Privacy, I decided to, all caution to the wind, install Mojave again and then install 10.1 version of Space Mouse. I followed the “simoncbevans Method” in hopes of controlling the Memory Leak problem and find that the memory is not maxing out after an hour of wild sketching maneuvers. That fact alone is worth all the time and effort(s).
The only difference that I’ve noted in SM, so far, is the more “minimal” view of the Radial Menus. The menus were a bit confusing at first look; but they work just as they did before, better actually due to the improved legibility.
If you had Mojave installed before updating 3Dconnexion you don’t need to restart with +R, that’s only a part of reinstalling High Sierra from Time Machine. Run the 3Dconnexion uninstaller first, download 10.6, and then go to System Preferences > Security & Privacy and turn off the Firewall before running the 3Dconnexion installer. Just after the restart from the installation has finished, go back into System Preferences and turn the Firewall back on. Hopefully you’ll have the same result that I have had.