add_filter missing argument when called from inside a class

Hi I’m calling the following from the constructor method inside a class:

add_action( 'manage_users_custom_column' , array( $this , 'add_column_to_users_table') );

Below is the (empty) method of the class that its referencing

function add_column_to_users_table( $column , $user ){ }

If I add this action from outside the class, everything is legit.
If I add this action from inside the constructor, I get the “missing argument two” error.

I thought it might be a problem with variable scope, so I added global $user to the constructor before the add_action function is called… still no dice.

The only way I’ve been able to resolve it is by changing the function in the following manner:

function add_column_to_users_table( $column , $user='' ){
  if ( $user == '' ){ global $user; $user = $user['ID']; }
 }

is this kosher or is there a better way to take care of this? Thanks.