Question: Does the ISP1302-BM support the meshed layer of BT 5.0? The idea of the customer is to be a part of the BT 5.0 mesh product family. 

Answer:  In Nordic environment, the mesh capabilities is dissociated from the BT version. Nordic proposes a nRF5 SDK for Mesh which is compatible with all nRF5 series chipset:
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk/dita/sdk/mesh_sdk.html
Therefore the Mesh can be implemented in the ISP1302-BM integrating a nRF51822-CEAA chip.
However, please note that the Mesh cannot be integrated within an ISP1302-BS just because of memory size which is only 128k, not big enough for the stack and the Mesh SDK.