As long as delete means "commit the deletion of unused files to source control", I agree. Though I don't know what kind of source control they had back then, and if they used it for such assets. In my opinion if something is not serving any current purpose in your code base it should be deleted from source control. The repo should be a reflection of the precise range of capabilities that you intend for the project to have; leaving dead vestiges of the past just laying around is like growing a garden and never cleaning it of deadwood and debris, giving more places for weeds to grow unnoticed.

I think we need better tooling for browsing historical artifacts that may be valuable in the future -- which I think is the main reason I've seen people intentionally keep dead code. Maybe the solution to that is to just tag the commit in which you deleted the code with a note on what it was so you can find it again.

Edit: An uncle comment mentions that this may have been a discovery from digging around in the CVS history for the game, so they may have kept the assets in source control after all! Some might reasonably take away from this to protect your source repo, but I think it's pretty cool it's possible to find these historical artifacts.