Quite relevant because what matters is the true count of useful applications - not the filler. By your reckoning (1:1000) that means RIM has 15 useful applications for BB10. Nothing to brag about. I've got 4 times that many very useful iOS apps on the devices I own and I've just scratched the surface. Android using friends of mine have dozens of useful apps on theirs.
More specifically it means that they have 15 useful applications *from this portathon*. I suspect the number to be higher - as it's fairly easy to port opengl games and html5 apps, outside of android apps.
They've already said they'll have over 70k apps at launch - it's not like this one-weekend event is their only effort to get applications on the platform. Unofficial estimates put them over 100k. That'll mean ~100 useful apps (if we stick with 1:1000) -- whhich is, frankly, on par with other platforms.
They've also previously said that they have 90% of the most popular 600 android and ios apps, and 18 of the top 20 apps .