It will be good to configure the editor to support readonly . We require this behaviour where we don't want users to change text unless a specific requirement is met.
The following How to article shows how to enable and disable Kendo UI Editor: http://docs.telerik.com/kendo-ui/controls/editors/editor/how-to/customize/enable-and-disable-editor
What makes no sens is to open the editor when the grid option "editable" was set to false.
Thanks for the proposal. You may consider to position a transparent div above the editor to prevent accessing it for editing when certain condition is met. You'll probably concur having built-in read-only functionality for a widget whose purpose is to provide editing capabilities (in essence) does not make much sense.