My question involves criminal law for the state of: Kentucky

My son is attempting to be released from prison to the Kentucky Home Incaceration Program. They have denied him because he was convicted in 1988 of Robbery 1. But, at the time Robbery 1 (1988) was not considered a violent crime BUT now it is considered a violent crime and the DOC is saying that this is why he can't be in program. Is this legal that they can do this? Looks like he would of not been grandfathered into the rules of 2010.