It's pretty likely that they
weren't reacting to runaway trim; on that we agree.
The trim wheels are large, painted mostly black with alternating, offset white stripes (so the motion is quite visible), and have a very distinctive clacker on them. https://www.youtube.com/watch?v=cQirIH_DuAs
It's possible that the crew fought to keep the airplane in a basic attitude flying configuration for several minutes without ever noticing the trim in motion unexpectedly, but that seems unlikely, particularly when the act of holding the nose up to hold attitude was accompanied by increasing nose down trim.
Minor note: there is no stick pusher in the 73. Those tend to only be installed on T-tail aircraft. Synthetic elevator feel increases, but no pusher only a shaker.
