Nemesis couldn't hit me while i was healing a downed survivor

Jets501

I play On the PC platform and basiclly playing with 4 friends two where downed during end game colapse and as he was crawling near the exit gate two of us stopped and started healing him in front of the killer nemesis he M1 3 times and even used his abillity which should have hit us as we was infected but nothing happened we just continued to heal them they got up and we all got out when realistically we should have been hit and forced out