He can lift the 405 without question.
The lowering.. the compensation he is having to do with all the shaking, I don't know about.
I can understand why he can't get to parallel, he is literally having his knees move out from under him slightly. It's like he is going down with the classic bar that moves the opposite to you the whole time.
If I were you, Brian, I'd get a set of wraps and wrap the legs wayyyy tighter than you can get with sleeves and see if you can get some stability out of that. It will be significantly easier but you genuinely lower the weight like someone who shouldn't be on that weight but you lift it like someone who should.