I wouldn't say "proved just the opposite" - but it certainly made the case for no existing detectable gateway effect - which is now explicitly stated by UK gov.
'Prove' is a bit strong but did you see my comments in that thread? And the quotes - certainly 'suggests' that - ie. IF you accept method/math, etc. I was going to list you in the people who might not buy into it but since you posted it, I thought I'd give you a pass.
Access to e-cigs associated with Decrease in cigarette smoking in adolescence
Access to e-cigs associated with Decrease in cigarette smoking in adolescence