From what I have seen Marqui Christian is not taking snaps from our Nickle corner NRC. MC has been taking snaps from Barron. Yes MC does play safety in certain situations usually is when safety LJ gets the assignment of covering a shorter
slot WR. go rewatch the Saints gm too.
Most of Marqui Christian's snaps this season (which are up dramatically) have come from playing the Mark Barron position. Wade is trending that MC (Strong Safety) replaces MB (inside LB'er) on passing downs.
IMO MQ has done a much better job in tackling than MB has but he is not the future nor the answer for the Rams.