All they know is, it is a dangerous  creature that has killed several people. The mind meld giving Spock  knowledge of the creature's motives hasn't happened yet.
		
		
	 
Okay, 
great comment, this is essentially the major flaw with the entire format of the show, as it relates to ethics/morals/and the PD, et al.
Look at what you wrote: "All they know is, 
it is a dangerous creature",..
and  therein lies the rub, as the UFP, KIRK and Company tell us they are  explorers, extending the hand of friendship in seeking out new LIFE (  not destroying that which they are threatened by, or do no comprehend),  new CIVIL,... you now the speech,.. the point is KIRK and CREW, and the  UFP are not in a moral position to judge anything or anyone,..
and  that means they cannot MORALLY take ANY action against anything which  would have any negative impact on its natural existence or evolution,..  regardless if the "Fangy Beasty" is about to eat your Geologist or not.
And  that would make for a pretty depressing show,.. "Men into Space, served  as a hot lunch";... this week, so-and-so gets eaten by a  whatchamacallit,..
THE UFP and its forces are the INVADERS  anywhere they go outside of the realm of the UFP,.. and are in no moral  position to judge the  slave/gangster/nazi/roman/greek/depression/computer-driven planet as  "bad", nor take any action against anything they find 'wanting" or  life-threatening to them,.. if they themselves are the invading  outsiders,.. AND truly subscribe to all the high-minded ideals contained  in their speeches about freedoms, rights, and IDIC, and so forth.
If they did, they couldn't go anywhere without an invitation, and certainly couldn't kill anything,. 
,....  or as they did so often,.. disrupt the entire culture of a planet, and  replace it with one more suitable to the UFP ideal and agenda,... (We  can help you build schools, feed 100 where you could only feed 1, bring  you teachers),... ah, indoctrination and absorption offered as "AID"
Basically  it is all about PERSPECTIVES,.. Planet of the Apes handled the dilemma  of cultural perspectives beautifully,... to Taylor, the Apes had taken  over his world and replaced it with their simian culture,.. BUT to the  Apes, "The Humans are an Infection!",.. perfect.
Since, the  Enterprise's mission is to seek out (invade) areas of space not already  part of the UFP corporate portfolio,.. they, regardless of the  rhetoric,.. are nothing more than Imperial, Expansionist,  Capitalists,... just like the good ol' USA.
and regardless of the  beautiful moral/ethic/ and aesthetic values espoused in a characters'  speech,.. in the end,.. if it interrupts FED BUSINESS,... WHAMM-OH!!!,..  unless the Organians or Metrons appear to nullify their aggressions  while "Boldly going where no HUN has gone before".
So in  point-of-fact, if SPOCK really subscribed to all that "respect all life  and the rights of everything, free to be you and me speech",.. he would  have resigned his post the moment KIRK gave the order to drive the  Enterprise around the Fly-paper colored-cube in space.
Actually  if you really compare what SPOCK is supposed to believe in, and what the  UFP actually does (not what they SAY they stand for), SPOCK would not  even have anything to do with the UFP,.. which really is just the I.S.S.  Enterprise, with better manners, and a better line of B.S.
So the whole show is one big moral/ethical contradiction, depending on your perspective, and it is worse for SPOCK, more than anyone,.. yet,.. there he is!
Frankly, while I obviously love the show, when it comes to the conflict of what the UFP SAYS it stands for ethically & morally, and what it UFP DOES in fact and deed,.. I second the Organians utter disdain for the Earthemen.
If your going to be a space-pirate, be an HONEST ONE, don't just wear the boots!