If a judge says you're in contempt, you'll get charged with contempt immediately - all the people required are present.
To charge him with defrauding investors requires a whole different group of people to get involved.
Additionally, those people need enough evidence to have a chance of conviction. "He refused to answer questions about it" is not actually evidence.
And it carries an indefinite sentence? That's crazy
To be held in contempt indefinitely you must "hold the keys to the jail cell" meaning you can leave at any time if you simply comply with the courts order.