I had no idea this issue had been identified. While I find this tool very useful, the project is seeming rather questionable to me now.
While this is true, it only requires the shim and grub to be copied for another distro.
From other comments there are a lot more blobs than just these two.
I think they did say that in the older thread. But for proper security, you shouldn’t have to trust them. You should have build tools that will re-fetch everything to create an identical build. That gives a clear chain of custody, which proves that morning has been tampered with.