I don't know, Mike.
Yes, an earlier image. The horizontal handle is connected to a couple of levers that are like field hockey sticks. When the handle is in the raised position--as in the photos, the blade is down. When the handle is down, the sticks rotate (rather like a cam) and raise the blade. There is a bracket on the deck that the handle slides into. The handle can be secured in the bracket with a cotter pin.
The several photos we have show the handle raised, and I infer that the blade is in the lowered position--I guess the way to confirm would be to study the position of the target. I don't know how you would disable the handle without removing it entirely.
Also, I don't have personal experience, but I bet the blade is darn heavy! I think it would take both of us and your son-in-law to lean on that lever and lift it!
Keith Hayes
Leadville in Sn3