Hello zyzzyva,
welcome to the Stridaforum!
Hmmm, me too, your idea sounds very logical…
Amuro posted here:
[url]How does the bottom bar latch work?]
the patent document of the quick release structure of the steering pin:
http://www.freepatentsonline.com/7681900.pdf
Example pic:
It should be no technical problem to add a locking mechanism to the steering pin (maybe the keyhole pointing downwards?).
However will the installing of a pivot in the steering pin not really secure the bike,
except -
the two bolts of the steering pin (part nr. 274), the right rear wheel bolt (part nr. 373),
the steering ball socket bolt (part nr. 273), the Allen key 3mm wormscrew which is securing the steering ball (not shown in the drawing of the owners manual 2008 page 12,13), and the pin of the bottom bar latch (part nr. 132 shown above)
-will also be secured (however).
Where and how do you want to place the pivot exactly?