If the police have a valid reason to stop you they have the right to your name and date of birth to ID you.
Since could have cited Ms. Bland for a pedestrian violation...i.e. a ticket....they had the right to ID her.
They were polite, explained why tjey were stopping her, they were calm, they were friendly.....
They were doing their job.
I had no problem with them talking to her. They were initially polite and she was initially polite. What was the point of asking for ID?