If you're wondering why it's so important to Elon that Starlink not be used for military purposes... I suspect it's two fold:
1. Because he's not a fan of killing people.
2. Because it turns Starlink into a legitimate military target.
The "It's a public utility" argument evaporates once it's being used to target and kill soldiers.
Elon Musk does not owe the Ukrainian people millions of dollars worth of satellite that the Russian government will blow out of the sky with complete impunity.