There is no requirement that the plea deal contain a cooperation clause or agreement for someone to cooperate. A defendant will almost always be given a chance to cooperate if they want.
Really, a cooperation clause in a plea agreement does little for a defendant - unless it is a binding plea where the parties agree to a specific sentence (which still has to be approved and accepted by the Court). The only thing a cooperation clause does in the federal system is give the government the ability to pull any acceptance of responsibility credit (typically a 3-level reduction under the sentencing GLs) or void the plea if the defendant doesn't cooperate.
In short, the absence of a cooperation agreement doesn't mean sh*t. If he cooperates, there's nothing to keep the government from filing a motion for a sentence reduction, regardless what the plea says.
