Identifying yourself by your gender can be harmless and doesn't need to be detrimental to society or equal treatment. But the premise of the blog is "the virtues of Legos for teaching math and engineering concepts to children."
If this premise is taken as true, this particular distinction in gender is harmful to equality of the genders. It's not just that the particular pink set reinforces certain stereotypes, but also that it's simpler and requires less abstract thought to put together.
That said; I'm sure the people at lego have done their market research, and have found that girls (or their mothers) find the "girly" sets more pleasant. Also the people at the outlet will have their reasons for a "blue isle" and a "pink isle".
I guess the morale of the story is for the parents. To not let themselves fall into the trap of the largest common commercial denominator, but to drag your daughter/son at least once through the "wrong isle" when buying toys in an unbiased manner.