The chapel in Linden, VA is what I would consider a hybrid chapel - half SSPX and half diocesan parish.
How do you gather this? How are they different from any other SSPX chapel?
If it's because people attend Mass at that chapel who are otherwise affiliated with the diocese (possibly people connected in some way with Christendom College), that would hold true in many cases. There is considerable drift among the various "ideological camps" of Catholic traditionalists. It's not unique to Front Royal.