"Scroll Cursor" besagt ja nur, dass du nach vorne rollen kannst.
Was dir fehlt ist "sensitive".
Ob dies allerdings auch mit Table-Functions funktioniert glaube ich nicht, da du die Sensitivität nicht an die Table-Function weiterleiten kannst.

Zumal man noch bedenken muss, dass Table-Functions häufig von API's o.ä. abhängen, die sowieso nicht sensitive sind.

@ExAzubi
Der Cursor ist im Gegensatz zu z.B. SQL-Server keine Momentafnahme.
Andere DB's arbeiten da z.B. mit Table-Locks oder Satzversionen um insensitive Daten zu garantieren.

ASENSITIVE, SENSITIVE, or INSENSITIVE
Specifies whether the cursor is asensitive, sensitive, or insensitive to changes. If
statement-name is specified, the default is the corresponding prepare attribute of
the statement. Otherwise, ASENSITIVE is the default.
ASENSITIVE
Specifies that the cursor may behave as SENSITIVE or INSENSITIVE
depending on how the select-statement is optimized.
SENSITIVE
Specifies that changes made to the database after the cursor is opened are
visible in the result table. The cursor has some level of sensitivity to any
updates or deletes made to the rows underlying its result table after the
cursor is opened. The cursor is always sensitive to positioned updates or
deletes using the same cursor. Additionally, the cursor can have sensitivity
to changes made outside this cursor. If the database manager cannot make
changes visible to the cursor, then an error is returned. The database
manager cannot make changes visible to the cursor when the cursor
implicitly becomes read-only. (See Result table of a cursor.) If SENSITIVE is
specified, the SELECT statement cannot contain a data-change-table-reference.
INSENSITIVE
Specifies that once the cursor is opened, it does not have sensitivity to
inserts, updates, or deletes performed by this or any other activation
group. If INSENSITIVE is specified, the cursor is read-only and a
temporary result is created when the cursor is opened. In addition, the
SELECT statement cannot contain a UPDATE clause and the application
must allow a copy of the data (ALWCPYDTA(*OPTIMIZE) or
ALWCPYDTA(*YES)).

Nur wenn der Cursor explizit als INSENSITIVE erstellt wird und die Daten temporär kopiert werden dürfen hast du deine Momentaufnahme.