sdmax2018 is a bitcointalk username not a telegram username.
You are reading too fast.
and the post you quoted above shows that the user is telling him about a telegram pm he/she sent.
What I'm saying is that the connection would be clearer if the @sdmax2018 bitcointalk account also mentioned @sande123 as his telegram contact.
Is Andruu the only admin on that bounty group? If so, I guess that should be enough to conclude that they are one and the same person.