I wouldn't be surprised if this was the case, given the investment that would be required to purchase and install manufacturing grade 3d printing equipment that could handle their volume, along with the time and expense in acquiring personnel that are experts in this arena.
The quickest and cheapest (initially) way into this game would be to out-source manufacturing, but we all know how that worked out for them previously.
In house manufacturing of 3D printed suppressors is certainly achievable for a company like DA if they decided to allocate the extensive resources and investment for this project. The question is really a matter of "if" they decided to pursue this new venture in-house. That I'm curious about.