"git fsck" not detecting garbage at the end of blob object files...

I was perusing StackOverflow this morning and ran across this question: http://stackoverflow.com/questions/41521143/git-fsck-full-only-checking-directories/

It was a simple question about why "checking objects" was not appearing, but in it was another issue. The user purposefully corrupted a blob object file to see if `git fsck` would catch it by tacking extra data on at the end. `git fsck` happily said everything was okay, but when I played with things locally I found out that `git gc` does not like that extra garbage. I'm not sure what the trade-off needs to be here, but my expectation is that if `git fsck` says everything is okay, then all operations using that object (file) should work too.

Is that unreasonable?  What would be the impact of fixing this issue?

-John