Total_worker_time over SQL 2008 linked server
When a query takes place over a linked server, does the local server
  record Elapsed time in place of CPU time, or does the remote server
  return the actual CPU time to the local server?


When executing a query over Linked Server the SQL Server session will enter an OLEDB wait while waiting for results, and that time will not be accounted for as CPU_time.   The linked server does not return wait stats.