Hi DW,
the spring loading on the sidestick means that if roll is all you want to control then the springs will hold you steady at zero in the Y axis unless you make an effort against them.
Correct.
However some some crews move their seats after take off into a more "comfortable" position. This places their hand and arm in a completely different position relative to the side stick. I think that's why Bonin inadvertently applied light back pressure whilst he struggled to hold wings level in Alt Law.
Since the crew didn't turn off the FD switches, when the FDs automatically reappeared, they were in modes HDG & VS. The crew seem to have simply continued to follow those erroneous commands.