He's asking for Wynn's head. He's not really waiting for justification at this point.

[Spike frowns. He doesn't like the thought of wasting the one night they have here either, but he likes even less the thought of being captured again. He'd rather die.

Of course, that's a pretty likely option at the rate they're going.]

Course, if we guess wrong, if we invade the wrong place and can't get Thomas...

[They'll do no one any good if they're captured. And he doesn't like to think on what they might learn from Buffy.

Lucky Des, he'll probably be killed quickly now that he's mortal and useless!]