Morgans writes:

What happens to parts of the aircraft if it clips a wing tip, and starts
spinning?

It generally will not, precisely because of that momentum thing. Instead, it
will continue flying with a damaged wing tip and some perturbation of the
flight path and handling characteristics.

It is certainly probable, and possibly even probable that some
parts of the aircraft could be flung in the direction of the crowd, if it
was spinning into the ground.

Just from hitting a wing tip against something? Do you really think the
insignificant force from clipping a wing tip can swing 200 tons of aircraft
through 90 degrees and a 200-foot radius towards a crowd? The laws of physics
don't allow that.