Northampton were aggrieved that Maitland was not at least sin-binned for clattering into George Furbank with his elbows during an aerial collision that left the England back needing lengthy treatment.
Referee Karl Dickson issued only a penalty and in making a quick decision declined to consult the TMO with the game just 25 seconds old.
To rub salt into the wound, the Scottish international went on to score Saracens' opening two tries as part of an unstoppable first half that produced a decisive 21-3 lead.
But last season's runners-up were worthy winners of a one-sided play-off as they set up a Twickenham showdown with either champions Leicester or Sale, who meet on Sunday.
Scrum-half Ivan van Zyl also crossed as Saracens scored three tries inside the first half-hour, with Owen Farrell adding all three conversions.
A spirited second-half showing from Northampton cut the deficit to nine points at 24-15 as Alex Mitchell and James Ramm scored tries.
But the five-time Premiership winners pulled clear in the final 10 minutes as a penalty try and Max Malins' score gave the final outcome a fairer reflection of a dominant performance by Mark McCall's men.
