YOu left out, "to the best of my ability". He used his best judgment as to how the matter of constitutionality should be addressed and the forum to use. He chose the best forum to make the final judgment and not the temporary stopgap of the veto. There is a reason that the founders made sure a presidential veto only survived the term in office of any particular president.. You may want to read up on their views of the "imperial" presidency.
Good catch. However, I disagree with his judgment here. There is no guarantee that SCOTUS will grant certiorari to address a bill that has been passed TWICE by the Right, when the Right will be the party claiming it is unConstitutional. That's playing dice with my beloved Constitution, and I don't like it.
He chose the best forum to make the final judgment and not the temporary stopgap of the veto.
Even IF SCOTUS grants cert, and even IF they vote the way that we hope, it STILL is not a permanent injunction against all assault weapons bans. The Left will merely read the language of the decision, rewrite the Ban with language that will not violate SCOTUS's reasoning, and ram it through Congress yet again. These are Leftist lawyers. Playing games with words and twisting them to do their bidding is what they do best. All President Bush accomplishes by promising to sign it is to further their aims, play the odds that someone else will fix the problem, and pass responsibility on to others. That is not what I want out of my elected leader.