Here's the thing though...the whole bone spurs thing only came about because Trump tries to portray himself as a tough guy. If he was just anti war and basically refused service like Ali or something, that would be one thing. If he was anti war and used his privilege to get a doctor to write him off for bone spurs, most people would understand and that would be another thing altogther. But he of course chooses the Trumpiest way of talking tough and bitching out.
The truth of the matter with Walz is that the worst interpretation of the actual facts is that he read the tea leaves that deployment was a possibility in the future and being 40+ years old with a new little one at home, decided to move on and run for Congress. It's easy to mischaracterize this 20 years after the events but when he started talking about running for Congress in mid 2004, public opinion of the war had already started dropping heavy (from low 70's approval to low 50's by sept 2004, and then low 30's by the middle of 2005 and obviously much lower among Democrats). It was an unpopular war among Democrats by then, and got even worse over the next 8-12 months.