The Silver Arrows' team principal says the decision is not clear-cut and potentially had another name to consider after qualifying for the Hungarian GP, which saw Russell outqualify team-mate Robert Kubica by 1.3 seconds to deliver Williams' best qualifying result of a disappointing season to date.
But Wolff wants Russell to develop out of the glare of a title battle, as Verstappen did with Toro Rosso before his promotion to Red Bull.
"I think you've got to consider that these guys come into F1 at a very young age," Wolff said.
"And there are exceptions to the norm, such as Max Verstappen, who was given the environment at Toro Rosso to learn, and to make mistakes, and even at Red Bull was given the room to make mistakes.
"It's impressive to see his progression in all kinds of aspects, as a personality – there's not one bad word about Honda, only good words about his team, the commitment to the team, and that is absolutely the right behaviour of a driver, I wouldn't expect anything else.
"But he was also given the possibility, even though he's extremely talented and well developed by his environment, to learn, to settle your strengths at Red Bull, and the Toro Rosso situation.
"I don't think you are given the possibility to learn in a Mercedes.
"Because you're being put in a car that is able to win races and championships, in a high pressure environment, and I think it can go terribly wrong for a young driver that has the talent to be become a world champion if he's thrown into that environment next to the best driver of his generation, who has been with us for seven years.
"And I wouldn't want to burn George.
"I think it would come too early, and on top of that I try to be respectful to all contracts we sign, and we signed a contract, we knew what we were doing with Williams, and this is where he's going to learn."
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