You seem to have slightly different file names
What I did was cd/Applications/GIMP-2.10.app/Contents/MacOS
./gimp
BradleyRossMacBook:MacOS bradleyross$ ./gimp
2019-10-14 22:14:25.061 gimp-bin[53568:2295958] *** WARNING: Method userSpaceScaleFactor in class NSView is deprecated on 10.7 and later. It should not be used in new applications. Use convertRectToBacking: instead.
Cannot spawn a message bus without a machine-id: Unable to load /var/lib/dbus/machine-id or /etc/machine-id: Failed to open file “/var/lib/dbus/machine-id”: No such file or directory
(gimp-bin:53568): GLib-GObject-WARNING **: 22:14:33.443: invalid cast from 'GtkMenuBar' to 'GtkWindow'
(gimp-bin:53568): Gtk-CRITICAL **: 22:14:33.443: gtk_window_add_accel_group: assertion 'GTK_IS_WINDOW (window)' failed
gimp_color_transform_new: using babl for 'Display' -> 'GIMP built-in sRGB'
gimp_color_transform_new: using babl for 'GIMP built-in sRGB' -> 'Display'
gimp_color_transform_new: using babl for 'Display' -> 'GIMP built-in sRGB'
gimp_color_transform_new: using babl for 'GIMP built-in sRGB' -> 'Display'
2019-10-14 22:16:54.585 file-png[53606:2297671] *** WARNING: Method userSpaceScaleFactor in class NSView is deprecated on 10.7 and later. It should not be used in new applications. Use convertRectToBacking: instead.
gimp_color_transform_new: using babl for 'Display' -> 'GIMP built-in sRGB'
gimp_color_transform_new: using babl for 'Display' -> 'GIMP built-in sRGB'
void gimp_gegl_convert_color_profile(GeglBuffer *, const GeglRectangle *, GimpColorProfile *, GeglBuffer *, const GeglRectangle *, GimpColorProfile *, GimpColorRenderingIntent, gboolean, GimpProgress *): converting buffer took 0.0253 seconds
... ... ....
I assume that MacOS/gimp is a shim program written in Objective-C. Does this sound right? When running the application in this manner, I think that it using the file permissions for the terminal rather than the GIMP application. Does this make sense to anyone who is more familiar with the code. Perhaps the Objective-C programs in the MacOS directory need to be updated?