SQL Server 2005 Management Studio bug???

I was composing an update query by hand today in Management Studio. I thought it was a simple SQL statement that simply joined my Control table to a Query table using two fields to link the tables. My original SQL looked like this:

update control
set    policyprocedure=q.policyprocedure
from   control join query q
       on control.activityfk=q.activityfk
       and control.systemfk=q.systemfk

Management Studio changed the SQL to be this:

UPDATE  Control
SET     PolicyProcedure = Control.PolicyProcedure
FROM    Control INNER JOIN
          Query AS q ON Control.ActivityFK = q.activityfk
          AND Control.SystemFK = q.systemfk

Notice that the SET now pulls the PolicyProcedure field from Control instead of my aliased Query (Q). That's not what I ordered!

I finally got the desired results (sans any changing of aliases by Management Studio) using this SQL:

UPDATE  Control
SET     PolicyProcedure = x.policyprocedure
FROM    (SELECT c.ControlID, q.policyprocedure
         FROM Control AS c INNER JOIN
              Query AS q ON c.SystemFK = q.systemfk
              AND c.ActivityFK = q.activityfk) AS x
         INNER JOIN
              Control ON x.ControlID = Control.ControlID

Is this a bug, or am I a moron who needs to study up on SQL? Maybe I should have used a CROSS JOIN and WHERE clause in my original update query instead of the INNER JOIN?

Comments anyone?