An understanding of the Association Incorporated Act and their own constitution is what is required. I have not seen their constitution. However, one would understand that there would be (as there usually is) a process for inviting members to an AGM, a section clearly defines members and a process for the calling of an AGM, which would include timelines and methods of providing notice to members and most importantly giving time to call for nominations for the term end board positions.
On that, normally just because a termed board position has changed by casual vacancy appointment throughout it's term, doesn't mean that it is not to be called for nominations if the position is at term end. Or any other casual vacancy appointments to other positions would then effect the calling of nominations for positions that were at term end. Most constitutions will stipulate term length of President, Vice President, Secretary and Treasurer and are normally 2 year terms and also term lengths of other director positions are typically 1 year terms. Furthermore, usually the President/VP/Treasurer and Secretary positions are alternating terms eg: President and Treasurer elected one year, Secretary and VP elected the next year).
Not withstanding all the reporting, auditing and appointments of Public Officer and Auditors among other business which would have to be organised to table at the AGM if it is not yet already organised.
Not withstanding, there are also regulations and processes in place for the calling of an SGM (which is normally meant for conducting business similar to that you conduct at an AGM but with special resolution, without having to wait for next AGM to come around again... normally an SGM is bought upon by members and most of the time consitutions will stipulate how that is done, eg: a percentage or certain number of membership base petitioning to call an SGM. It is very irregular to conduct and SGM immediately following an AGM, as you would normally be able to conduct such business at the AGM anyway. Unless, process has been met to have an SGM which could give rise to changing what was resolved at the AGM (perhaps, can't think of any other reason for it really, otherwise why not just do it at the AGM or just have an SGM).
Who knows unless you are in the inner sanctum and I don't know, because I am not even related to the situation... just looking from the outside. But, action of calling an AGM on this time frame and in this manner seems questionable. I guess that is what people are pointing out.
Maybe it is a case that people new to association committees/boards very rarely understand the governing laws and regulations they are accountable to and then often make technical mistakes which allow others to perceive a lack of transparency or take exception to (it happens all too often)... maybe it is deliberate and maybe not.
Whatever the case, if the SSO was keeping an eye on governing the sport then there would be tools to help overcome this being problem (such as governance training and workshops for all new committee members across the state for all affiliates, or at minimum the sharing of the ORS and Sport SA fact sheets that are readily available regarding good governance and understanding the laws and regulations that govern association incorporate bodies, as well as the responsibility of being a director of such an entity... whilst these positions are generally volunteer positions, they still have an executive level of responsibility and accountability to them.
If from the inner sanctum they have followed their constitution and the act itself, then there are no problems. However, it seems people are perceiving that this has been handled in such a way that gives rise to question that. There is always an associated risk of not following due processes in business (no matter what the business).