I looked in the RMSS Spell law and there is no prohibition on it. In RMU there is a specific prohibition against both disruption spells and black channels.
If you want to stay RAW, then I might say that you can't really choose your black channel: it is supposed to be a cultural thing. So if you made Londarin's hand the culturally associated BC, then... good luck (it does not carry a specific RR penalty though)
If you stay in the wording of the spell (which I sometimes have to pull from the box of GM tricks) then it may only disrupt flesh... So I'd only allow BC I: 1 and 3.
Then again: is this worse then Long flesh destruction (yes this a bit of a stretch but it says; ANY single lower level spell and since this may be used as ANY lower level spell you can vary effects on each target (BIG stretch), or break limb, collapse lung or Disruption V...?
This is one of the reasons why I do not like people taking sorcerer. This caster has some very nasty spells, which do well as adversarial spells, but are a little too advantageous for PCs... and game breaking for too clever PCs.