Starting with the next RhinoWIP and Rhinoceros 5.1, you can use the following command in Terminal to stop automatic update checks:
defaults write com.mcneel.rhinoceros MRDisableCheckForUpdates -bool YES
Starting with the next RhinoWIP and Rhinoceros 5.1, you can use the following command in Terminal to stop automatic update checks:
defaults write com.mcneel.rhinoceros MRDisableCheckForUpdates -bool YES