IrrestibleForce

I think it's more likely that it's been patched on whatever server Castle may be playing/testing on.
Having been on more than a few of the STF's with CMA, i can verify that the buffs on LR do indeed drop if you can get him away from the towers, at least playing on Pinnacle and Guardian.
I wouldn't be expecting this loophole to last forever, but no point in not exploiting it while it's still there.