@AOG
To decide whether this incident was racist, we need to indulge in some conjecture, which I know a number of regulars, who post to your threads, take strong objection to. You may do yourself, so I apologise, in advance.
We should conjecture whether the same individual would react to a group of 5 BME individuals by approaching them, challenging them with a "where are you from?", instead of the kind of greeting which won them a "20-strong group of friends" and play out the rest of the incident in the same way.
Likewise, for a mixed race grouping, would he spray them all, for being "strangers" or would he spray one colour but spare others?
His friends evidently enjoyed the spectacle so should think themselves lucky not to have been identifiable, on CCTV, for joint enterprise, conspiracy to commit GBH, failure to report a crime (he handed himself in, maybe too little time for them to take the initiative) or whatever is appropriate.
The article does not say whether he stole the spray, while drunk, or whether it was something prepared at home, so carrying it could be said to be premeditated.