Yes, going through all of the Editable JGoText objects and call setEditable(false) is the most precise thing you could do.
The only predefined alternative is to call JGoLayer.setModifiable(false) or JGoDocument.setModifiable(false). But that of course would disable a lot of other kinds of user modification besides in-place text editing.
The right thing to do would be to override JGoText.doMouseClick to check your view for some boolean property that you define, such as isEditingEnabled(). If false, doMouseClick would just return false. (Same goes for doMouseDoubleClick too, I guess.)
But if you don’t want to replace all of your JGoText instances with those of a custom JGoText class that you define with this override, you might be able to override JGoView.setEditControl(JGoTextEdit) to be a no-op when your view’s isEditingEnabled() predicate is false.
I haven’t tried this to make sure there aren’t any undesirable side-effects.