It is hard to tell. The only reason that I can think of "pursuing CZ-9(11)" is to meet the date of 2030 moon landing.
But there are two questions about 2030. Did CNSA give a big margin of 2030? That is did they take into consideration of change of configuration like 11 to 21? If they did, then version 21 may not push over the 2030 milestone, then there is no need for version 11.
The other question is that 2030 is just "around" not a date set in stone. I think this could be the case because CNSA has in most cases stated "around". So 2033 still fit the statement. Version 21 could be on time, meaning no need for version 11.
In any case, CZ-9(21) is to replace the full sized CZ-9(11) with four boosters. The only purpose of them is moon base building and Mars landing.
Based on the thought (about 2030) above I think I agree with your assessment that there is no need to pursue CZ-9(11).
2030 for initial manned moon landing, or 2035 for the ILRS?
Because the aim to achieve a manned moon landing
before 2030 (per the slide), AIUI, was described to be achievable using two CZ-5DY launches (a triple, and a single), so it wouldn't need either any variant of CZ-9 to begin with
The ILRS, as I understand it, consists of multiple phases between 2025 to 2035+, and the earliest in which an ideal "super heavy" is projected to be needed will be in the early 2030s to launch bigger payloads to the moon, and a manned launch to the ILRS will only occur sometime after the mid 2030s.
What I wonder is whether the initial launches to the ILRS can be done with CZ-5DY, depending on how heavy the payloads are, meaning the "requirement" for the super heavy capability of CZ-9 might not truly emerge until the early 2030s, which could allow CZ-9(21) to be pursued with complete abandonment of CZ-9(11) without compromising their projected launch plants.