We have contemplated supporting read-only documents several times in the past. The problem is that because Script Debugger is an editor, people expect to be able to edit and have their changes saved. We fear people may become confused if they forget a document is read-only, and then see Script Debugger’s blocking of edits and saves as a failure.
We’ve considered banners above the editor and other UI tweaks to communicate the read-only state.
Maybe you could implement an opt-in-model, i. e. a setting in SD’s preferences which is off by default and comes with a warning dialog, when clicking the OK checkbox? (I mean clicking the setting is what makes this feature generally available. Unchecked SD behaves as if this feature isn’t implemented.) Just a thought.