He's probably the usual scammer that infests Gog since months.
He creates many alts to enter giveaways, steals codes whenever he can, upreps himself and dereps others with bots, spams users, spreads lies and attacks people.
Unfortunately Gog is powerless, so every trade here now is a risk
, expecially with accounts created from 2015.
GOG isn't powerless, if you have enough proof , send this to the support.
using bots is violating GOG policies (re-read them)
Of course , blocking an account doesn't prevent to create a new one -_- , on this matter GOG is powerless till they decide to allocate more ressources.
As i already said; letting them doing this behaviour isn't good for GOG's business. in the long run.....
However, trading there is a risk, that's not new , simply the number of impersonators & scammers have been increased to a point,.... i totaly agree.