Tobirama is in Minato's league in my opinion and slightly better, but he's not in Naruto's league or Hashirama's (they're just... different, although Hashirama is still much more powerful). Tobirama's not killing Naruto, unless he's forced to fight without using Kurama's chakra (which is a possibility).
I understand you saying Minato can beat Tobirama seeing as Tobirama has displayed no feats so far, but do you seriously think Naruto can take on Hashirama, when he only has half of Kurama's chakra at his disposal? Hashirama made Kurama (with all its chakra) who was clad in Perfect Susanoo go to sleep. Flower Tree World potentially solos the two considering that if Sage Mode Hashirama uses it, it will cover the battlefield and more, which means they either flee (forfeit) or get knocked out.