The breaking of the ear happens all the time and isn't related to whether it is cast, forged or a billet. It doesn't take much to snap them off, especially if when you are installing the pin. I'll bet you used a mallet or hammer. JB will work as mentioned. Once it has set up and you've cleaned it up, use a c-clamp to install the pin and press it into place. Make sure you lube the pin and holes well. It may also help to either squeeze the leading edge of the pin in some pliers, or file it to give it a little contour. Many times the sharp edge of the pin catches the aluminum in the hole and gets hung up.
Anodizing doesn't add any strength to the lower, nor does it harden the aluminum. That looks like a NOC or Tanneryshop lower, so they are already hardened to T6. All that anodizing does is to protect the lower from corrosion, and provides a hard shell to resist wear and surface damage. It also provides the ability to absorb the dye, but it definately doesn't add any strength to aluminum.