You are correct that that has been some time since the knowledge base article for this update. My apologies as that was an oversight on our part.
We do now support Garritan libraries and the ARIA Player on M1-based Macs with the use of Rosetta 2. These are not currently Apple Silicon Native so you will need to use the plug-ins in a host program that is also using Rosetta 2.
Plogue's Sforzando Player, which works as an alternative to ARIA Player, and which plays all the Garritan products I have (GPO5, GIFF), is available as a Universal Binary for both Apple Silicon and Intel.
I guess there may be two motivations, firstly potential customers may find solutions elsewhere never to return, and secondly it really doesn't reward existing loyal customers. Dragging their feet on implementing for Apple silicon I find disappointing and will make me wary of investing in their products in the future. I guess it's a question of how much they're willing to hurt their sales vs. the cost of recompiling. Shame. the CFX Grand is a great instrument, I love it, but I may have to move on soon. I'm not prepared to work under Rosetta 2 for a piano sound alone.