A Firewall is different from Triage. They are putting a Firewall around their somewhat safer Northeast seats, especially, rather than going for the true tossups. I don’t think this will help them retain the House, with so many races in play. It may limit the damage, however, thus the name Firewall.
If they’re trying to save 218 seats, I’d say it’s a firewall.
If they’re trying to save 146 (prevent 2/3 majority), I’d say it’s triage.
I don’t see the R’s getting 67 Senate votes though.