There had been multiple cases in which people claimed that they are satoshi

kinda funny but dont have a valid proof.
If he can login from Bitcointalk profile then i would believe 60% of his authenticity of being Satoshi.
Also I think that Satoshi is not a one person, I think He is a community who made this forum a team of individuals who are into crypto , one of the pioneer people that invest and develop a powerful coin and exchanges, this is only my opinion.