They recently started pushing out videos for the Pathfinder. Around this time the Platinum disappeared. It is very possible that they integrated everything into the Pathfinder.The SmartSiren Platinum page is inaccessible for me as well. It was accessible as recently as October, 2020:
SmartSiren Platinum is a siren/light control system and remote control head that provides a high-level of customizable control capability. With FS Convergence Network technology, the serial communication significantly reduces installation time.web.archive.org
I'm unable to find a relevant marketing update from Federal Signal as yet.