Jason: It seems that would be the case for a radio group, but I have just verified on a test page that this is the way the code is inserted - a blank array - when you create a DA form with only a radio group. Please try that - it must be a bug.
In fact, I can make that block of code work by inserting a single value into that empty array:
ValidatedField("projectsupdate","display"):array($row_WADAProjects['display'])))
With that code, the radio group is shown properly populated whether its value is yes or no.