Homer overwrite local files?

[akash329d]

Bit confused by this excerpt from the README.

After copying the .git directory (the actual data contents of the repo) to your home directory, it will rungit reset --hard HEADto "rehydrate" all the files of the working copy in the home directory rather than in the place it was checked out. This is to ensure that any overwritten files will have a diff to show you what changed, and none of your files that currently exist in the home directory will be accidentally deleted.

I'm confused how the overwritten files will have a diff in this case, if you do a hard reset won't that immediately overwrite local files with the ones you have in your dotfiles repo? (With no way of reverting it).