Has anyone sought political asylum from australia ?

Yes.
Julian Assange (founder of wikileaks)was seeking asylum in another
country's embassy. (can't remember which one.)
If he returned to Australia or left the overseas
embassy) he would be arrested and deployed
to Sweden to face criminal charges there.
Julian was a threat to Australian, American
and other Governments. He leaked many Gov't
secrets etc.
( I guess there have been others before, but not
many.)