Really not true. Minutes were taken during meetings where these decisions were made and it’s possible to see what people actually were thinking and saying rather than speculating.
That being said, the firebombing of Dresden was absolutely as a warning to the Soviets. The RAF put out a memo saying that they “want to show the Soviets what Bomber Command can do.”
Wasn’t he literally on the Russian payroll? Cashing checks from gazprom.