Out of the box you can use UI profiles so that those users cannot see the salesperson grid.  You cannot make it non-editable.  In terms of making it non-editable you can have a custom OE screen created or look at Orchid's Extender product which would allow you to disable editing of the salesperson values but still allow you to see them.  Extender will also allow you to do a bunch of other things so I would suggest looking at it vs. a custom screen.