Ha ha, yeah Revan even complains about 'the betrayer' but doesn't notice that Scourge is infact standing right next to you! Scourge keeps quiet as well. Well planned Failware!
You get Scourge after Revan is rescued in the timeline of events. You going back to run it with Scourge in your party has no effect on the timeline or the story. The fail here was on your part, not Bioware's.