To me it's pretty simple. He says what he means and means what he says. When have you heard a politician do the same? Granted he isn't always artful but a lot of what people "think" he's saying isn't at all accurate.
He has not disparaged our men and women in the military. Not even close. Basically he's saying McCain's "heroism" is over blown. I'm not saying I agree, but I do think "hero" is applied far too often to far too many who don't deserve it.
What McCain endured while a prisoner of war was beyond comprehension, yes. That he chose to stay behind when he could have left was heroic. Yes. Should that, however, give him a pass for the rest of his life even having not lived up to expectations? I think something like that is what Trump was getting at in a very tortured manner. Pardon the pun.
Rather than exaggerating the circumstances of gaffes, or bending them to suit their purposes, the Republicans should look at what's stealing their thunder. Here you have a man who is beholden to no one. No Chamber of Commerce nor Business Round Table is going to dictate to him how to think. So far the other candidates, those who are politicians, not outsiders, still dance around everything that might be threatening. Not so Trump.
What you see is what you get. If you don't like him, fine. He doesn't care. If you do like him what you hear from him is the straight forward Donald Trump. That he is loud, egotistical and often just plain obnoxious is of no matter. To many his being the anti-politician is all they need. A breath of fresh air.
One day soon I expect he'll have to come up with specifics. He may have some difficulty with that. Just as the politicians don't know what to do with him, he'll find dealing with Congress equally as difficult. Maybe.
Don't forget Obama has set the precedent for going around Congress to get what he wants. It wouldn't surprise me to see Trump do the same. The difference being I think he would tell us first exactly what he would do and why.
One other consideration for the Republicans. If they force Trump into a third party run they might as well kiss the presidency good bye. Enough people will vote for him, no matter the label, to skew the results.
Perhaps they should tone down their own rhetoric and let the Trump flame burn itself out. If they don't tend to their own business rather than trying to end Trump's they may well find themselves on the outside looking in at their own territory.