I don't blame Bush for those attacks -- but no, he didn't "keep us safe."
That's particularly true when you recall, as Bush supporters never do, that the Iraq War, a conflict he chose to enter based on mistaken intelligence, killed more Americans than the 9/11 attacks.
Almost 5,000 American troops were killed in Iraq. Tens of thousands more were wounded, many seriously. Bush did not keep them safe, by virtue of sending them to fight an unnecessary war. Even if you think that the war was necessary, he didn't keep them as safe as he could have, due to his administration's shocking negligence preparing for the conflict.
The bungled execution unarguably cost lives.
If you're unaware of it, read "Blind into Baghdad" by my colleague James Fallows: "The U.S. occupation of Iraq is a debacle not because the government did
no planning," he concluded, "but because a vast amount of expert planning was willfully
ignored by the people in charge." An excerpt can't do the article justice, but here is the thesis that, by the end, is persuasively demonstrated:
Almost everything, good and bad, that has happened in Iraq since the
fall of Saddam Hussein's regime was the subject of extensive pre-war
discussion and analysis. This is particularly true of what have proved
to be the harshest realities for the United States since the fall of
Baghdad: that occupying the country is much more difficult than
conquering it; that a breakdown in public order can jeopardize every
other goal; that the ambition of patiently nurturing a new democracy is
at odds with the desire to turn control over to the Iraqis quickly and
get U.S. troops out; that the Sunni center of the country is the main
security problem; that with each passing day Americans risk being seen
less as liberators and more as occupiers, and targets.
All this, and much more, was laid out in detail and in writing long
before the U.S. government made the final decision to attack. Even now
the collective efforts at planning by the CIA, the State Department, the
Army and the Marine Corps, the United States Agency for International
Development, and a wide variety of other groups inside and outside the
government are underappreciated by the public. The one pre-war effort
that has received substantial recent attention, the State Department's
Future of Iraq project, produced thousands of pages of findings, barely
one paragraph of which has until now been quoted in the press. The
Administration will be admired in retrospect for how much knowledge it
created about the challenge it was taking on. U.S. government
predictions about postwar Iraq's problems have proved as accurate as the
assessments of pre-war Iraq's strategic threat have proved flawed.
But the Administration will be condemned for what it did with what
was known. The problems the United States has encountered are precisely
the ones its own expert agencies warned against. Exactly what went wrong
with the occupation will be studied for years--or should be. The
missteps of the first half year in Iraq are as significant as other
classic and carefully examined failures in foreign policy, including
John Kennedy's handling of the Bay of Pigs invasion, in 1961, and Lyndon
Johnson's decision to escalate U.S. involvement in Vietnam, in 1965.
The United States withstood those previous failures, and it will
withstand this one. Having taken over Iraq and captured Saddam Hussein,
it has no moral or practical choice other than to see out the occupation
and to help rebuild and democratize the country. But its missteps have
come at a heavy cost. And the ongoing financial, diplomatic, and human
cost of the Iraq occupation is the more grievous in light of advance
warnings the government had.
George W. Bush failed to keep us safe, partly because he happened to be president when al-Qaeda succeeded in perpetrating a major attack, partly because various other attacks happened during his tenure, and most unforgivably because of his reductionism and hubris, pursuing a needless war of choice on false pretenses and executing that war poorly for years on end, in part because he elevated loyalty to his immediate underlings above having competent help.
The "he kept us safe" talking point is factually inaccurate. In closing, it's worth noting that the president doesn't swear an oath to keep us safe, but to protect and defend the U.S. Constitution.
Bush failed at that too.