The thing about the Scylla sacrifices vs Eurylochus wanting to leave then men on Circe's island behind is the different levels of intent.
In the case of Circe's island, they were blindsided. They were lured into a trap that they had no way of anticipating, and after that what's done is done. In Eurylochus' eyes, the witch has them now, what's done is done, and any attempt to rescue them is likely to lose them more men.
In the case of Scylla, on the other hand, Odysseus had all the foresight. He knew exactly what going through the lair of Scylla would cost, and he intentionally set his men up to be killed. He essentially pays Scylla in human lives for passage through the lair.
Even if we say that there was no other choice, there were other ways of going about it. The most important thing would be to tell the men about Scylla beforehand. That way, those who didn't want to risk death could disembark and start a new life on a different island; not everyone is willing to die to go home, and Odysseus had no right to decide that for them.
Furthermore, its the fact that Odysseus never even tried to find an alternative solution to just standing by and watching Scylla eat his men. THAT is why Eurylochus is so mad, he says as much at the beginning of mutiny.
"When we fought the cyclops, you were quick to hatch a plan
And when we fought with Circe, it was you who left behind no man
But when we fought this monster, we didn't take a stand
We just ran"
Its not just the fact that he traded his men's lives like they were tokens, its the fact that it was his first and only plan, that he didn't even try to find a solution that didn't result in death, and just stood there and did nothing as his men died all around him.
In situations that are unexpected and sudden, you can be forgiven for acting in less than ideal ways. But when you have all the knowledge, all the advanced notice, then you have the power and the responsibility to at least TRY to find a different solution. That's what condemns Odysseus in my eyes, and why I'm willing to cut Eurylochus slack for his reaction to the Circe situation.
Odysseus had all the power, so he has to carry all the blame.
