Simulcast technically means "at the same time." In the case of the RICS system, and many trunked systems, if you have a simulcast "site", then all the towers in a specific area will transmit all the same traffic as if they were one "site". Some trunked systems have "standalone" sites, where there is only one "tower" associated with the site. With East Simulcast 700, for example, there are many towers associated with that "site" that all broadcast the same traffic.
You probably wouldn't hear dispatch traffic from Malibu since those units would be using West Simulcast, either 400 or 700. However, if a subscriber radio (a radio that is affiliated with the system), turns their radio to that channel/talkgroup, the system will recognize that it wants to listen to that channel/talkgroup and activate it on that entire "site", which would be East Simulcast 700. When that radio changes channels or gets turned off, then the "site" will no longer put-out traffic from Dispatch-10.
Hope that all makes sense.