My understanding is that these towbarless tugs are approved at speeds up to about 30 kts.
Sure, this incident appears to be proof that it was towed around a corner too fast for the conditions at the time, but I too (as has Keg) have seen towed JQ A320's charging up and down Twy S at speeds that seem quite quick.
Then again, I've taxyied A320s at 30 kts in the past (within A320/A330 FCOM limits) and heard silly comments over the radio - clearly directed at me - that suggested it looked fast too (one pearler was "V1, Rotate" from an anonymous genius). Never had it in A330s, so it must be a 'relativity' thing; a small aircraft looks faster at same speed than a big 'un.
It'd be interesting to see if the engineering provider's SOPs include speed limits when towing around corners.
One other thing that just occurred to me was this; what if they were half way through a corner, and ATC gave them a late direction to stop or hold short of a nearby taxyway - the sudden shift to brakes might cause the whole shooting-match to go pear shaped (try it in a car one day...).