again, ettercap is a sniffer, so, if the device that needs to be sniffed (the NIC in this case) has some restrictions such as firewall restriction, what do you think ettercap will do?
the sniffer will capture whatever comes through the NICs and if nothing comes, due to the restrictions, then ettercap will capture nothing.
is that makes sense?
because your question doesn't make any sense to me

Btw: there is no such thing called ARP firewall, there is firewall and ARP. 2 completely different things.