Some NSPs return a response that explicity identifies DMCA as the reason for the article not being found, which Alt.Binz can use to autopause, but others don't - just generic 430, which sometimes can just mean 'try again later'.
A more general and future-proof alternative to what you're suggesting might be simply to have a configurable option to autopause if X numbers (or X %) of articles are missing, with whatever response. Then you can decide whichever minimum threshold means DMCA is most likely.