If you choose to use two space width tabs, and I choose to use eight space tabs, what does a one hundred and twenty column page width mean? What do your edits look like on my monitor? What do mine look like on yours?
If you are both using tabs, for him everything is going to be indented with "2 space tabs" including your edits, and for you it is going to be indented with "eight space tabs", including his edits.