Is it true that SoaS is no longer being actively updated?
Yes, SoaS is no longer being actively updated; but you can update its latest version with the Diva Updater function. There’s a step-by-step guide on the website homepage (http://simonastick.com/).
I must add that I’ve been working with Sim-on-a-Stick almost every day without even once having to use the Diva Updater function. Besides downloading the latest version of SoaS - that's SoaS 0.8pf (OpenSimulator 0.8.0 post-fixes) – the only thing that has changed since 2012 is the viewer I use with it: started using KokuaOS instead of Singularity.