And to add a supplementary reason to the ones already mentioned by P@nther and Krieghund, consider the following argument.
The area under dispute shows two borderlines: the yellow terrestrial one between Newfoundland/Labrador and Quebec, and the blue maritime one between SZ 116 and SZ 106. The yellow one runs horizontally west-to-east, then make a 90-degree turn and runs vertically southward. The blue one runs horizontally east-to-west, and connects with the vertical component of the yellow one, forming a right angle.
In most places on the map, the end-points of borderlines are clear and unambiguous. WolfPack points out, correctly, that this particular intersection of two borderlines in question isn’t clear and unambiguous: the point at which the yellow and blue lines meet is a fuzzy dark line rather than a hard transition from yellow to blue. And it’s quite correct that this creates ambiguity, as is shown by the fact that an official clarification once had to be issued on the matter. WolfPack’s “I think you may change your mind that NF doesn’t border SZ106” follow-up post seems to indicate that he doesn’t agree with the official clarification. The supplementary argument I’d make, therefore, has to do with the concept of the mapmaker’s probable intent.
If you imagine that the yellow and blue lines are solid red – i.e. if you draw a long vertical red line through the middle of the vertical yellow one and a long horizontal red line through the middle of the horizontal blue one – there’s no question that they form a right angle and that the territory of Newfoundland/Labrador lies entirely within that right angle, and thus that there’s no connection between Newfoundland/Labrador and SZ 106. This would fit with Theory A: the mapmakers intended for that right angle to be a hard, clean border, but an unintended graphic error made the border look confusingly fuzzy. This explanation has the virtue of being both simple and plausible.
Theory B, on the other hand, goes like this: the little fuzzy dark line between the yellow line and the blue line was deliberately put there by the mapmakers in order to connect Newfoundland/Labrador to SZ 106. This theory seems neither simple nor plausible. If the mapmakers genuinely wanted to connect Newfoundland/Labrador to SZ 106, why would they do so by using a “pixel-wide trace” technique which is used nowhere else on the map, and which is so open to debate, rather than by cleanly and unambiguously giving Newfoundland/Labrador a coastline on SZ 106, which would have been quite easy to do?