So, you have an issue with a specific group: anti-war voters in 2001, who subsequently supported any politician, of one party, who voted for the wars. You consider them immoral. Wouldn’t any such voter be immoral, regardless of party?
You’re entitled to your opinion, of course. But if you only vote for politicians who are always right, or who always vote the way you want them to vote on every issue, you would never vote for anyone.
Historical example: In 1915, in WW1, Winston Churchill was the architect of the Gallipoli Campaign. A complete, utter bone-headed fiasco, with 250,000 allied casualties. By your standard, no British voter should have supported Churchill 24 years later, in WW2, when he led his country to victory, because to do so would have been immoral.
A personal example: I voted for P43 in 2000 because I was angry at the antics of P42. (Something about a gal and a cigar.) So, I based my vote on morality. But P43 was the architect of the wars that followed. Hoisted on my moral petard. Ouch.