Whether this is good for your son depends on why he was red shirted, how likely he is to be a key player next year, and what he can do to get better before next year. He shouldn't commit a second year to that program without having a solid basis for believing he'll be on the field for his redshirt freshman year in 2016.
One of the biggest issues associated with redshirting at a JUCO is understanding how the academic progress rule will affect him if he tries to transfer to a D1 school after three years at the JUCO.
It's not enough that he'll have two years of eligibility and two years remaining on his five year clock. And it's not enough that he'll have a bushel full of college credits. He must have enough credits that will transfer and count toward his degree to satisfy the academic progress rule. There are strategies for making it work, including taking upper level classes in summer school and taking less than a full time load during a couple of the JUCO semesters.
Strongly recommend you talk to someone like Rick at Informed Athlete who can give you specific advice for your son's situation.