One minor point folks aren't mentioning that I think works in Neimann's favor - Carlsen is known for enjoying the Catalan, and the opening in the game was essentially a Nimzo/Catalan hybrid. This fact makes Neimann's supposed pre-game prep a bit more palatable. Everything else (postgame interview, past history, Twitter antics) seems to work against Neimann though.
My question is - if Neimann did cheat, how? Doesn't seem like something that can be done easily in an OTB tournament.