I would say it stops when it stops being an honest ADMITTED mistake.
The guy already knows he made a mistake. I mean you can keep telling him he is wrong but he admitted that right off the bat.
I think we all draw the line well ahead of poaching at night.
There is pretty big gap between not seeing a 3 inch antler and poaching at night.
The "line" is also kind of relative. I don't thinks its ok to go out and shoot illegal spikes on doe tags on purpose or all the time but I don't think its a big deal to make a simple minor mistake every once in a while.
I don't thinks its wrong to point out the mistake either......but how long do you ride a guy that already knows he made a mistake?