7 - access callback get currently checked path
Based on my research, I checked first the current_path() function and in it's code it gets the path by $_GET['q'] w/c indicates only getting the values fro the URL so this wouldn't work.

I also checked the access callback and access arguments' functionality and initially I noticed that access arguments are meant for the actual use that you are trying to bypass where links needs to be checked to let Drupal know if it will display a link. The only way is does this is by specifying the access arguments.

In my opinion, the access arguments array standardizes where the "access specifications" would come from like this menu's access specs are basing on the second and third arguments. So developers would know what they're dealing with by looking at the access arguments array and user the access callback just to do mostly logic.

I hope this could help.