They absolutely had a say in where their money was invested. They voluntarily chose Enron stock, because it was available to them at a discount to market value.
and when the company was collapsing they were prohibited from pulling their money out
During the time when Enron stock fell from $85 to $15 they were fully able to pull out. They held on until the stock fell below $15 and the plan administrator froze the plan assets for 60 days.
Again, that was their decision and theyn were informed well ahead of time that the plan would be frozen if the administrator saw fit.
Show proof or admit that you're just making it up. Typical 401k plans at that time didn't allow pull outs or transfers while still employed.