Please refer to this APNI–APC page: https://biodiversity.org.au/nsl/services/search/names?product=APNI&tree.id=&name=Sporobolus+diand&inc._scientific=&inc.scientific=on&max=100&display=apni&search=true
Quotation: " Text: A common weed in Malesia and Asia, but as yet not collected in Australia. The name Sporobolus diandrus was formerly used in Australia to include species now regarded as separate (S. laxus and S. sessilis), differing in the degree of nakedness at the base of the inflorescence branches. Sporobolus laxus has a longer naked zone and S. sessilis has spikelets to the base of the inflorescence branch. " .
This states that this sighting most likely identifies to _Sporobolus sessilis_ or _Sporobolus laxus_ (and _Sporobolus diander_ / _diandrus_ does not really occur in this continent Au).