We can assume from the descriptions that while they've come into contact with beings with meat or meat-like structures as part of them, they've never encountered intelligent beings made of meat. And so they necessarily can't know all that much about the possible states of meat. So your "surely" is canonically wrong.
You can argue they ought to have known about that, but that is based on assuming life like ours is common, and the point of the story is that this is an assumption we're making from a sample of one planet. In the in-story universe it is also canonically doubtful that life like ours in common, given that they clearly know of many other species, and can explore at FTL speeds, and yet still haven't run into one like ours.
To me it feels shallow to criticise a story based on ignoring premises of the universe the story is set in. Criticise the premises, by all means, and argue it doesn't fit our universe. That's fine. That gets you to the point of the story: To get you thinking about why we should assume life like ours is common.
You can argue they ought to have known about that, but that is based on assuming life like ours is common, and the point of the story is that this is an assumption we're making from a sample of one planet. In the in-story universe it is also canonically doubtful that life like ours in common, given that they clearly know of many other species, and can explore at FTL speeds, and yet still haven't run into one like ours.
To me it feels shallow to criticise a story based on ignoring premises of the universe the story is set in. Criticise the premises, by all means, and argue it doesn't fit our universe. That's fine. That gets you to the point of the story: To get you thinking about why we should assume life like ours is common.