Trying to do this between button bar segments, doesn't appear to work. However, the original conditional formatting on the original button bar segment, can be transferred to another object, such as a field and the conditional formatting from this can be transferred back to another button bar segment.
I would love to be able to drag-n-drop button bar segments between button bars and I've always wondered why it hasn't simply appeared as part of the functionality.
In the same way, I wonder why the conditional formatting, visibility, etc, can't be transferred from one object to another by dragging the icon ( option drag, command drag, control drag - what ever is preferred ) from one object onto another.
I use this method a fair amount, and it has worked between button bar segments for me. The last two comments on the question you linked are the key. The object with conditional formatting must be higher in the stack order than the object without.
I regularly copy conditional formatting (but not in button bars). Just bring the conditionally format object to the front and then select it and the other objects you want to conditionally format. When you bring conditional formatting up, it will display the rules from your front object. It's my best undocumented tip!