the probability of the LHC producing a black hole moving slower than escape velocity (tiny already)

The calculation is in appendix F of the paper. Apparently the probability is tiny for some values of the black hole mass and large for others, so if those others are at all plausible the total probability isn't tiny (all this being conditional on black holes being created in the first place).

Anyway, I've said my bit and since we all agree this scenario is too improbable to be a concrete worry, I'm going to bow out of the discussion.