The correct answer to this would be immediate relief from their positions. If they sat in their offices and did nothing the president could give them an order to perform their jobs and when they failed to comply, relieve them.
Some of those generals have left the military. In order to punish them, their retirement benefits and demotions to lower lower level ranks, would be appropriate. Some could be brought up on charges of insubordination and breaking the UCMJ commitment.