The rule that they are talking about is the OWP pilot program that was announced December 22, 2014. Because you must have legal (or implied) status to be eligible, they're claiming that this is not their fault, because even by allowing your status to expire (which is what they did), you wouldn't have been eligible for the normal OWP that Inland applicants can get AFTER they reach AIP.
This pilot program only happened because of the Inlanders that were tired of waiting for OWP, so they started a petition, contacted the media, held peaceful demonstrations and...CIC listened to their cries for help!
EDIT:
Ate the very least, your lawyer should have explained that you would fall out of status, but that you would `probably' be ok, and let YOU decide if that's what YOU wanted. Since they did not, they totally dropped the ball, IMHO.
Most people, if given the choice, would NOT want to lose their status!