Assuming you are correct and the C/O is invalid then it would be an illegal occupancy. However one wonders why a c/o would be issued if the premises is not up to code. The LL can remedy the issue by executing the neccessary repairs and obtaining a c/o. Under NJSA 2A:18-61.1 (g) and (h) the relocation issue is some what complex. Please call for a consult.