I’m not able to two finger scroll through the list of riders that I could join when beginning my Zwift ride. I’m running Mac OS 10.10.2 on a 2013 Macbook Pro.
On my Mac trackpad I can scroll through the list by clicking on the slider bar and then three-finger scrolling over the bar. You may have to change your trackpad settings to enable this.
But yes, it really should be fixed to work correctly with the two-finger scroll.