Free? Like, there some form of distribution or something one can do if they own the book?
Also: In the games I've played, we've been pretty flexible with the icons. Like, we could use each of the champions as an icon (or the nation their from), as well as the Devourer and the Prophet. That gives 9 icons right there. Or if one wanted, one could even adapt the 'factions' in this forum for the same purpose. Granted, it's not the nice 13 that comes with the game, but there's also the alternate rules that exist for 7 icons if one wanted to try and adapt it that way. But methinks the biggest issue lies not with adapting the system, but finding enough people who know/play 13th Age.
I suspect it has less to do with a fondness for Pathfinder, and more to do with the cost and familiarity of it. It would seem that there are versions of Pathfinder that are both digital and free, and when trying to get a group together, both of those points are ever so appealing.