Except that two issues are covered together in the article. While it's true that they also do this for racing, this guy was pulled over for having a headlight out, they popped the hood (I assume they asked his permission, he was an idiot not to refuse it) and found an engine with no serial number.
It does say that 5 of the 6 vehicles had stolen parts, but the last one apparently was just for street racing - and it sounds like this is a procedure that may be fairly common.
I’d like to whomp ‘em up side the head for endangering others, but taking a multiple thousand dollar car seems a bit much (except of course if it was stolen).