'Snow Cloud Peak' blinked and issued a warning to himself internally.
Thinking he could casually seek out Hill to question Rose was indeed quite presumptuous... That's a notorious Spider Queen, even if she wouldn't target Little Bear, it doesn't mean she wouldn't trip up William through him.
Though always knowing the high-level NPCs in this game are acted out by corresponding AI brains, he still loses some vigilance because he knows they're NPCs. He can't continue like this.
Of course, Rose's conspiracy isn't scary. Her strongest trait is her shamelessness, daring to do anything... The reason 'Snow Cloud Peak' loses cautiousness is he genuinely doesn't think her schemes qualify as real conspiracies.
But, how to say it... shameless people would never blame their failures on their own mistakes; the norm is to toss the blame onto others, irrelevant to reason.
