Even IF the account was bought (what I dont believe as this has 0 advantage for a highroller) this guy still lost a lot of money with stake. So treating him like shit is yet another shady move by stake. But they really like shady stuff.

Also if he provided all the evidence that he is the rightful owner, why does nobody actually show the opposite?

As long as stake doesnt give a better reply this case will go on for the next days I guess.