It was sold at a time when most didn't even know xur existed and when most did not know what strange coins were let alone attain them, bungie knew this so they strategically allowed xur to sell it at that time just like they put thought into every exotic they decide to let xur sell. Iam sure there's a reason why they decided to sell it, maybe something better will come out or they realized that their exotic loot system is flawed so they decided to gift everyone time will tell...