Did Kate see an abductor? No she didn't but she turned the findings ("the whoosing,slaming doors") that she encountered and constructed that into a hypothesis - an alleged abductor (AA) that used the window for exit. I can see why she said the window now for if Tannerman was the abductor and he left via the front door there is no way for him to lock that door behind him, and the front door wasn't found open.
Since Gerry and Jez were outside the steps she must have discounted the AA using the patio door because of Gerry and Jez' presence on the road.
But in actual fact Kate didn't know about Tannerman at that stage, but the logic still applies. As Kate found all gates and doors closed at her check she must have discounted the AA using the patio door and the gates.
OK in hindsight I don't think her diagnosis was perfect.
Soz, Rob, but Gerry and Jez were further down the road near the corner of the alleyway betwixt the Tapas area and the apartments. Watch Amarals latest video. He has the spot more or less spot on (according to Janes account on the Cutting Edge Video and Jezes hand drawn map and account.)
I agree with your logic about having found the gates and doors closed. Also maybe the fact that the patio area was lit by the street lamp opposite and in full view of the tapas group only 50 metres away may have been on her mind.
Amaral stated that no abductor would have used the patio door entrance with it being overlooked so closely by the family friends. For once, i agree with him.
I dont think that the patio door entrance was used by either an abductor, or by Madeleine on her own ... and neither was the window.
AIMHO