My guess is that the concern is that folks will bubba their guns and then attempt to have Horse pay to repair the receivers, alleging he provided incorrect instructions, etc...
If you have one of the czechpoint plates, you can have two pin holes (two holes in czechpoint plate aligns with two pin holes for sear and trigger on the receiver) to properly align for drilling. I'd imagine some forum member who has one, or is upgrading to this one, would be willing to share their old plate as a template, potentially a pass to next member daisychain could be arranged...
From pics, my only gripe here is that this side plate doesn't look like it would be able to support an ambi safety, which I was hoping to see Horse incorporate...