There, the Kingpin reveals to Osborn that Spencer Smythe did not die in the explosion back in "The Spider Slayer", but that he escaped early on before the explosion ensued at OsCorp and was met up by the Kingpin. But rather than killing him outright for his failure with the Spider Slayer's goal to kill Spider-Man, the Kingpin sees that he may still have some future use for Spencer, so he places him in chronological suspension.
There, the Kingpin discloses to Osborn that Spencer Smythe did not perish in the explosion back in "The Spider Slayer", but rather he evaded early on before the blast at OsCorp and was reunited with the Kingpin. Instead of eliminating him immediately for his failure to accomplish Spider-Man's demise with the Spider Slayer, the Kingpin perceives that Spencer might still be useful in the future, so he puts him into a state of temporal stasis.