Absolutely not...
Seminar is just a ticket to express interest for the guys who do not have any connections with NB.
The NB immigration department is in constant touch with employers and at times, employers request them to bring some candidates so that they can hire them. So - they brought the 3rd ticket - open category.
So that means open category can express interest even if they do not have any connection to NB and have not attended any seminar. You guys in my eyes are priority (first priority is - having a job or connection in NB).
If you are in open category NOC and still have not received ita, means there might be many people in the same NOC who have got better score than you. I recommend to keep trying. BTW, I don't think 2173 is open category anymore....