if they can produce a warrant for this data, there's no reason why the site cannot comply. But to get the warrant must require a judge to grant it, and it must be lawful.
Lawful is an interesting term. Patriot Act was voted in and is the law of the land. It allows for NSLs and other rather controversial if not unconstitutional practices.
Warrant is not a must. This is not a movie. You would be surprised how many companies give you what you want just by calling as LEO.
