Y'all are not very good at sticking to a plot.
"why would they do that, instead of this?" Squirm, modify, rationalize, if, but...
They wouldn't. I say: They do THAT, period. This is how they think, period. They're alien minds, they think differently than us. Why, Squirm, modify, rationalize, if, but, doesn't work with them.
They find out the ship is named after a battle. To their mind, we glory in war, we're a disease. They kill us. Period. It's done.
Hence, my earlier thought that it might not be a good idea to name ships after battles. That's all I'm sayin'.