He's mostly correct but I'm not quite so negative about it. In fact, I would give it four stars (out of five). Where we do agree, is that this 'interpretation' definitely works better in scherzo/andante order. In andante/scherzo order - the way it is recorded - I would only give it three stars.
The first movement is very 'chopped' and very controlled. But in a way, I like it because Vanska clearly makes the obsessively repeated low A in the basses and - sometimes - cellos, the main musical line. What makes me think that scherzo/andante is the right way to play this baby, is that Vanska makes the coda to the first movement sound 'hollow' - very Shostakovich like. He absolutely sails through the climax that happens about 25 seconds from the end - the moment where Mahler takes a few seconds, to take in the much earned victory of the "Alma" theme over the dark march in A minor. It's hard to describe, but it's as though Mahler is saying, "our business is rejoicing, our business is rejoicing" (like Shostakovich).
If Vanska had taken the scherzo at a really fast clip - like Chailly/Gewandhaus - then yes, I could accept andante/scherzo order. But his scherzo is at exactly the same tempo as the end of the first movement. It works much better as a negation to the ending of the first movement. In fact, just remove the last note of the first movement and segue immediately into the scherzo and, VOILA! - you'd get a solution to this whole inner movement nonsense that would absolutely work. It's as though the running back is about to score a winning touchdown, only to the fumble the ball to his opponents on the one yard line (who then run with it 30 yards in the other direction). A unified Part I that makes perfect sense.
The finale is quite strange, but I think it mostly works. Yes, there are problems. But what I like is that Vanska makes just two climaxes tower over everything else in the movment: the second hammer stroke (which is reinforced by an incredibly loud smash on the gong), and the final A-minor explosion at the very end of the symphony. In fact, those two events tower over every other loud moment in the entire symphony.
I really like Vanska's slow movement, but I like it in the third spot. The fresh, outdoors-y 'Alpine' moment is absolutely wonderful, almost magical in fact (about 7 minutes in).
So yes, it is definitely a 'different' Mahler 6 that calls for patience and restraint on the part of the listener. Whether that's good Mahler or not, is in the ear of the beholder. I think the two huge climaxes in the finale pay off (second hammer stroke and the end). I wouldn't, however, make it a first recommendation. I think it would be a good supplement to a more 'traditional' rendition, such as Bernstein/N.Y., Boulez/VPO, Abbado/BPO, etc.