Angularjs: call one route without the hash?

Question

I know that with $locationProvider.html5Mode(true) I can remove the hash from all routes, but I don't want that.

I use an API that makes a callback call to my app, but they explicitly forbid that the callback url contains a hash. Therefore, I need to provide a callback url without hash, and currently the only url that can be accessed without hash is the /index.html.

I guess that handling the callback in the index.html would be quite ugly, so the best option would be to create some rule in the web server configuration to create a valid url without hash and redirect it to my app.

Does anybody know about other option to solve this issue?

Bonus question: Why would someone (LinkedIn in this case) forbid to put a hash in the callback url? Is there any security issue with that?

Thanks!