I figured out a consistent way to get anti aliasing to work on my MBP 2016 running macOS Sierra.
For this to work you need the MacBook plugged into an external monitor, I have had it working on 2 different external monitors.
1 - Launch Layout and move the window to the external monitor.
2 - Right click on layout viewport to SketchUp model and select 'open with SketchUp' (SketchUp should not be running)
3 - SketchUp should launch on MacBook screen with much finer line work.
Don't know why it works but is does.