No authority does not imply they have to bend over and parrot governments' messages.
WHO could have simply requested permission to send an early investigation team, and if refused, warn the rest of the world that investigations were refused.
They could have been the canary in the coal mine and let other governments, who do have power, pressure the one that refuses to cooperate.
And by the way, the WHO is not an NGO. Its membership is open to all nation states, but exclusively for nation states, similarly to UN.
https://www.who.int/sidcer/links/en/
" World Health Organization
An inter-governmental organisation whose objective is the attainment by all peoples of the highest possible level of health."
WHO could have simply requested permission to send an early investigation team, and if refused, warn the rest of the world that investigations were refused.
They could have been the canary in the coal mine and let other governments, who do have power, pressure the one that refuses to cooperate.