Since the script is based on sys.dm_db_index_usage_stats, it only returns unused indexes that exist in sys.dm_db_index_usage_stats. Other unused indexes can be found by a different query with "WHERE NOT EXISTS (select ... from sys.dm_db_index_usage_stats ). Something like this:
SELECT DB_NAME() AS DATABASENAME,
--OBJECT_NAME(B.OBJECT_ID) AS 'Table',
obj.name as 'Table',
B.NAME AS 'Index',
idx.rowcnt, idx.used/128 'MB', substring(b.type_desc,1,20), 'No Stats', is_unique as 'unique', is_primary_key as 'primary'
FROM SYS.OBJECTS obj
INNER JOIN SYS.INDEXES B ON obj.OBJECT_ID = B.OBJECT_ID
join SYS.SYSINDEXES idx ON B.OBJECT_ID = idx.ID and B.index_id = idx.indid
WHERE NOT EXISTS (SELECT *
FROM SYS.DM_DB_INDEX_USAGE_STATS C
WHERE B.OBJECT_ID = C.OBJECT_ID
AND B.INDEX_ID = C.INDEX_ID)
AND obj.TYPE 'S'
and B.NAME is not NULL
and b.is_unique = 0 and b.is_primary_key = 0 -- don't include unique or primary keys
ORDER BY obj.name , idx.NAME