Michael almost took offense to the idea that Crowley would tell him to be careful, but even his considerable pride wasn't great enough to blind him to the truth. His pride and self-confidence had blinded him to the possibility of the Winchesters stopping the apocalypse, he'd ended up getting thrown into the Cage the last time he discounted them and let his feelings for one of his brothers distract him. That would not happen again and Michael wouldn't reject wisdom simply because it came from a demon. A demon who had likely heard him thrashing and screaming in the Cage.
Crowley wasn't an ordinary demon anyway, he'd apparently withstood Lucifer, Castiel, the Winchesters and every other sort of thing that could make life unbearable. Maybe he wasn't a wholly reliable source for information, but he had a talent for survival that some would call admirable.
"I intend for whatever I plan only to involve Castiel and myself. No need to make the Winchesters unsettled, or make the rest of Preya fear me more than they already seem to." Michael knew he was already referred to as 'the big gun', that his name was brought up when some officers of the law made threats and that many of the regular citizens were distressed by him joining the police force. They would get used to it, and it wasn't as if Michael was truly doing anything that would cause anyone discomfort yet. Paperwork and performing his own little internal investigation on 'Mac', nothing that would have him dealing with the public yet. He was in no rush.
He cleared his throat and tried to return himself to a calmer state. "Thank you, for your willingness to share and for your concern."