Can we monitor the ping state of Access Points via WLC Manager after they are discovered
No, it is not possible to monitor the ping state of Access Points via WLC Manager after they are discovered.
Spectrum will model AP by consuming information (IP & MAC) from WLC MIB data.
But once APs are modeled, reachability would be taken care by Spectrum core functionality (like every other model).
So once AP is modeled, Spectrum changes model status (or raises alarm) based on direct ICMP reachability.
According to Spectrum design, reachability of any pingable model is monitored directly by Spectrum (same hold good for AP models as well). It uses WLC MIB info for other attributes but not for reachability/contact status.
This means it is not possible to be able to manage the AP model state via the WLC- It has to be directly managed via the AP itself.