Will the placement of a MOCA filter as shown below work to effectively isolate a cable modem from MOCA traffic? The POE filter is shown in red below:

Note that this configuration does not employ a separate splitter downstream of the modem such as is shown on the product information page for WF-803M. For clarity, the configuration that uses a separate splitter is repeated here:

In other words, is "Splitter 2" shown above really necessary? Can't the modem be isolated without the splitter as shown in red in the first configuration above?
Please use the second the diagram to add the filter.
With the first diagram, the upstream DOCSIS modem still can affect MoCA adapter.
Need a filter to block it.