Hi,
to make date field readonly you also need to disable click event/URL in field's header and write a method to make it clickable again. This can be done using JS/JQuery but I haven't any useful examples.
For these purposes in our env we are simply switching mandatory state:
detailMakeReq("sched_start_date", false);
detailMakeReq("sched_start_date", true);
And users in most situations aren't fill unrequired empty fields for no reason
Regards,
cdtj