I read the report. It is the most comprehensive work I have seen on this subject.
I personally agree with most of the findings. Although it is a relatively "small" problem at present, the potential for catastrophic attacks mandates that we train our staff to recognize the signs of prison radicalization, recruitment, and terrorist organization. I have been in contact with our counterparts in the Middle East and Europe, and we must be proactive in our measures so that it does not affect us as it does their prisons. But I do not believe we should equate groups of radicalized inmates with gangs, even if they do share some of the same characteristics. Their determined worldview, their potential for staying under the radar and for perpetuating catastrophic terrorist attacks transcends the criminal gangs.
Of course, this is my opinion alone and does not necessarily reflect the opinion of the USDOJ or the FBOP.
If readers want my personal view, they can read it at
http://stat.squarespace.com/further-reading/
Then click on "Terrorists in Prison".
Eric