Anatoliy is right: the devil is in the details.
Assuming your P&S is binding without that addendum, then have your agent to thank them for offering those inspections, and relay that you're still going with your own inspections this time. (That's an indirect way of saying, "No, I'm not going to sign that addendum.")
Relo deals can be cumbersome because of the process and paperwork. The agreements they ask a buyer to sign generally are not open for negotiation, but understand this is the way these deals go. If you don't allow the process and paperwork to overwhelm you, Relo deals can be very appealing. Contrary to what you are feeling now, they generally are homes that have been inspected carefully with major issues addressed in order to expedite the sale of the property.
So take a deep breath and ask your agent to request the inspection docs. Hopefully your agent has had some experience with Relo deals so she can calm your jitters and help you see beyond the process so you can evaluate whether this is the home for you.
Unwavering Commitment to Service
Hope this helps and that things will pin out for you.
Century 21 Shaw Realty