Not dishonorable, but still disqualifying
I think there's a parallel between the controversy over Bush's military record and the 2000 presidential election fiasco in Florida. In both cases, the focus on disputed facts has distracted people from drawing important conclusions from the facts that noone disputes.
Starting with the disputed vote in Florida, I wish that Bush had won the state with a clear victory, so we all would have then focused on the fact that he would not be president in a country with a democratic system, because Bush lost the national vote. There has been no attempt to fix the electoral college since then, and little focus on whether Bush should moderate his policies towards the position of the candidate that won the vote. It looks like we may have another close election, so it very well could happen again that the losing candidate will be in the White House next January. We've learned nothing.
Getting back to Bush's military records, there are disputes over whether strings were pulled to get him into the National Guard to keep him from Vietnam, whether more strings were pulled to put him ahead of other candidates for pilot service, whether his apparent failure to take a required physical that was necessary to allow him to continue flying constituted a dereliction of duty, whether he was AWOL in Alabama, and whether his military records have since been purged of damning documents. Maybe Bush is as pure as the driven snow regarding these disputes. What's undisputed though is that Bush supported the war in Vietnam, he was the right age, he was unmarried, and he had no children. In other words, he was in the category of the most appropriate person to go to Vietnam.
So was it dishonorable for him to fail to volunteer to serve in Vietnam, as Kerry had done? No - you can believe that something is the right thing to do, even if it's dangerous, without having to automatically volunteer yourself for the position. As long as you take no unethical steps to avoid an unpleasant or dangerous duty, you don't have to take the next step of seeking that duty out. So long as Bush is as pure as the driven snow on the disputed facts, then, he did not act dishonorably.
But he still should be disqualified from the presidency. We're not talking about the failure to perform jury service - this is about the Commander in Chief ordering people in harm's way, people who are married, people with children, people who even oppose the president's policy, when Bush was not willing to take the same risk.
This isn't even about the modern military being all volunteer - it's not all-volunteer anymore. The military has issued stop-loss order to crucial personnel requiring them to keep serving after their stints have expired. These people are in the same position of draftees, of having to take risks they did not assume willingly. More about this issue in a posting for another day.
In 2000 this might not have mattered so much - ordering soldiers into combat was only a possibility, not a certainty, and Gore's service as a military journalist in Vietnam did not contrast as strongly as Kerry's does with Bush. Now we live in a different era. Bush's actions may not have been wrong (maybe), but they were not enough to allow him to be president.