I had to try it since the setting could be set. I wanted to see if a READ_ONLY setting would be enforced in a new database. I expected that it would and thus cause some problems (say you run a script to create your database and then perform the necessary database settings, add files, or create objects) and then you run into errors because the database would have been READ_ONLY. Alas, my suspicion was wrong and the setting does not get enforced.