Well, digital transfer is not ever an exact restoration or preservation of a film, because the media are so utterly different. The color models are different, the way they are viewed is different, the size of the viewing screen is different, the resolutions have different characteristic pros and cons, etc. Therefore there will always be some decisions and some compromises made. As long as a digital restoration involves making decisions in an effort to most closely replicate what viewers witnessed in a best possible theater projection of the time, I am ok with that. But adding effects or doing things that go beyond what viewers would have witnessed in a theater is going too far.

The garbage mattes are a grey-area (no pun intended), in that they were present in the film, but not necessarily in a viewing. So if a digital viewing of them presents as an "artifact" a greater likelihood of their visibility, and thus an alteration of the experience from what a theater-goer would have experienced in the best-possible theater setup of the day, I would be ok with a restorer deciding that a digital version in which they are removed would be closer to restoring what the film experience was like.