Then why give the vaccine?? Think!
No clue.
The summary you linked to indicates that the 88 year old woman was unresponsive at the time and 14 days post COVID (not sure if that was test result, start of symptoms, or observed recovery).
Could have been a mandate, family / POA request, a long shot attemp to try something, a nefarious plot to kill her off. There is nothing in the report indicating why the shot was given, but there is indication that the staff thought she was soon to pass.