Googling around (and discarding the #standwithdan hashtag that is for the Texas Lt Governor, who said that old people should be willing to sacrifice themselves for the economy) I gather it's a response to the folks who want to end the lockdown in Victoria and are likening Daniel Andrews to a dictator etc.
It looks like the case numbers are way down in Victoria, though, which is hopeful and also suggests lockdown measures do work if people actually follow them, or are compelled to.
Seems like every country has folks who don't care about stopping the virus as much as they do about going to bars and restaurants and so on. Sadly, in the US, our shutdown states haven't fared as well, maybe because they keep loosening rules every time we see a slight improvement and our police are pretty much not enforcing the rules that are in place anyway. Also, governors aren't allowed to restrict travel between states here, so even if we got down to zero in one state, new cases would come in.
So I stand with Dan too! Glad to see someone is making headway against this pandemic.