In ideal world that guy could have an LMG or any number of other good weapons. You need at least 1 sniper in your team if you want to make it “ideal”. In an ideal world that guy would also not run head first into an LMG.
You can pop stim but after that he jumps on you in melee, unless you have someone else there to help you’re not going to live. Again, arguing about LMG fire and 1v1.