Except that Hinch is a Canadian...

Ok, so he's American, too. Just like Carlos Munoz is...
Anyway- I see Rossi's win in a different light- the underdog won. Yes, he was with Andretti, but since he's a rookie, and this is the first year that Brian Herta is part of Andretti- it's also easy to look over that.
Part of Indy's appeal is that the little guy always had a chance- you could build your own car, and do really well. The 80's were filled with teams at the front (for a short while) on Buick power. That really went away with the spec cars, and the lack of enough cars to have a serious bump going on.
Nobody dug at (any) Andretti for wanting to go to F1, nor Sebastian Bourdais or anyone else. So I don't see that as a big deal. Actually, I see it as a benefit- as a high profile Indy car winner could go to F1, which will raise a lot of awareness of that, too. And he will always be welcome back in an Indy seat.
It's not as if Indy was short of local boys who were doing well.
Also- given the desire to have US born drivers, what's the deal withe love of Penske (ZERO US born drivers) and the hate of Andretti (3 of 4 US born drivers at Indy)? Heck, even Ganassi only has one American- and Kimball was born in the UK. Some of the other teams, the support is clear- although no US born drivers for Sam Schmidt. Then again, people have it against Ed Carpenter due to his relationship with the guy who wanted to bring Americans back to Indy- and his team is 100% US born.
Having a young rookie win gives Indy a shot in the arm. Better that he was US born. Even better if he goes to Europe, does well, and THEN comes back.