Review of GetUserId() Usage

Greetings,
 While looking through the GetUserId() usage in the backend, I couldn't help but notice a few rather questionable cases
that,in my view, should be cleaned up.
 
 As a reminder, GetUserId() returns the OID of the user we are generally operating as (eg: whatever the 'role' is, as
GetUserId()respects SET ROLE).  It does NOT include roles which we currently have the privileges of (that would be
has_privs_of_role()),nor roles which we could SET ROLE to (that's is_member_of_role, or check_is_... if you want to
justerror out in failure cases).
 
 On to the list-
 pgstat_get_backend_current_activity()   Used to decide if the current activity string should be returned or   not.  In
myview, this is a clear case which should be addressed   through has_privs_of_role() instead of requiring the user to
SETROLE to each role they are an inheirited member of to query for   what the other sessions are doing.
 
 pg_signal_backend()   Used to decide if pg_terminate_backend and pg_cancel_backend are   allowed.  Another case which
shouldbe changed over to   has_privs_of_role(), in my view.  Requiring the user to SET ROLE for   roles which they are
aninheirited member of is confusing as it's   generally not required.
 
 pg_stat_get_activity()   Used to decide if the state information should be shared.   My opinion is the same as above-
usehas_privs_of_role().   There are a number of other functions in pgstatfuncs.c with similar   issues (eg:
pg_stat_get_backend_activity(),  pg_stat_get_backend_client_port(), and others).
 
 Changing these would make things easier for some of our users, I'm sure..
       Thanks!
           Stephen