A simple explanation might be an attempt to taxi with the tug still
attached.
Fullwings,
No, I don't think so. The available evidence in post 5 and now backed up by post 44 indicates clearly that the nose gear was forced to port against the braked tug, leaving skid marks almost worthy of the tug driver's underpants. Most likely cause of this is substantial assymetric thrust. Every picture tells a story if you look. Check post 32.