NDP-12 is changing line 39 on page 3, after the word “time”. The effect would be that it would be within a reasonable time after the offence was committed at a place that was within reasonable proximity of the place where the offence was committed.
Again, this is to avoid the scenario in which either you would have the posse chasing somebody over days, or, as was suggested quite forcefully, one in which the private investigation groups would see an opportunity to turn themselves into investigative arms of the owner and potentially offer a service that would include going after somebody and finding them.
Phrasing it as “reasonable proximity” avoids the consequence and dangers associated with grabbing somebody at a shopping mall because you see them the next day there, or at a bus stop, when the person doesn't know who you are, why you're grabbing them, or what you're doing. The problem can be avoided by saying that the citizen's arrest is designed to deal with situations such as in the David Chen case, when a guy comes back to the store, whether it's within an hour or within a day—or two days, for that matter.
Again, “reasonable proximity” uses the word “reasonable”, but it indicates that there's some constraint as to place.