I respectfully disagree on the safety vs manufacturing point* but, as you noted, this discussion is moot if SNY lacks legal standing to bring the suit.
*The cursory in vivo data to which you refer is hardly out of the ordinary for an ANDA; for instance; bioequivalence is often tested in vivo. The weight of NVS/MNTA’s satisfactory response to the FDA’s concern about immunogenicity relied on the in vitro data furnished by the companies.