Assigning an studio shortcut to the escape key is impossible since the escape key is also what press when you want to cancel binding a key.
The “Clear Selection” button is bound to Escape by default. The only way to bind it back to Escape after clearing that shortcut is to restore the default keybinds.
EDIT: Moved to the proper section. Whoops.
Its not really… safe to assign a key to escape, as its usually used by so many different elements (app fullscreen, canceling out of a window, etc.) It may be difficult to make sure that escape is devoted to your functionality only.
This was my first reaction as well, but Escape is included in the default keybinds. It would therefore make sense for developers to assume that they can rebind the key, or at least re-assign it to ‘Clear Selection’ after (accidently) changing it.