No. I completely disagree with this post, and I use Deadbeard as my main zombie right now. His projectiles are fine. And he most definitely does not need a damage buff. His spyglass shots are 20 each, with the scatter shots being 40 each. Deadbeard is fine.
And Barrel Blast, in addition to being a way to kill several enemies at once (making it a great way to defend the point or take the point in objective modes), grants you armor. A lot of armor, so it doesn't need an invulnerability phase.
I've got an Elite Deadbeard right now and I can easily speak to getting plenty of kills with his normal shot. I can also attest to successfully using Barrel Blast to clear groups of enemies. Deadbeard is fine.