Why the Sniper doesn't work in MNC (PC)

Match earlier, one player on the other team had a 3-600 ping and went Sniper
It wasn't by much, but he still managed a positive KDR of, I believe, 12/10

His average ping was about 500

Your point being?

That there's either something wrong with the class or the netcode

You can go positive as any class with high ping (with the possible exception of the assassin). Not something amazing.

With 500 ping it should be amazing that he could hit anything, but then again ping compensation has become commonplace

sniper rifle trusts clientside data, not serverside. pretty sure.

you are correct, at least that's what i've been told all along.