Different strokes, I guess. I'm a standing player, although I feel I play better seated. The trouble is several hours of sitting gives me terrible back pain (I have a bulging disc and crumbling vertebrae).
I'm going to investigate playing cello position while standing. I really like the way the left hand fingers sit flatter on the fingerboard in that video (fantastic bass playing there BTW). I've always played conventionally, with the result my fingers have become somewhat deformed, particularly the pinky, from the "curl".
The problem I see is that there will be little to hold the bass from spinning when in a standing position, unless I stand to one side a little and the rear of the upper bout sits against my sternum.
Sorry, I'm just musing here......