Just appending a note for anyone else finding this. Hidden settings doc is here: https://sourceforge.net/p/skim-app/wiki/Hidden_Preferences/ And this specific setting is "SKDisableTableToolTips", so defaults write -app Skim SKDisableTableToolTips -boolean true should disable it.
Disable TOC hover text previews/add preference for same
It looks like "actualize_gestioip.sh" expects to only run on linux, where "/bin/sh"...