That "small" crossing handles around 300,000 passenger vehicles a year. So, over the 5 year period you mention, there were 1,500,000 passenger vehicles passing thru. That number doesn't include buses, trucks and other commercial vehicles.
Using the 216 weapons number given in the article, that means about 1 in 7000 vehicles had a weapon confiscated (assuming it was only one weapon in each confiscation, which is way too low). To look at it another way, five years is 260 weeks, so they confiscate less than 1 gun a week.
I guess what more there is to say is "there is no significant problem with illegal weapons being brought into Canada from the US."
Or perhaps "Canadian customs agents do an incredibly lousy job catching people bringing illegal weapons into Canada" is what needs be be said if your point is Americans are somehow all gun toting fanatics hellbent on bringing their weapons of death into that peaceful utopia known as Canada."