Get it inspected.
Offer to pay for the inspection if it passes and agree to buy the bike should it pass. An downed bike could look fine but be in rough shape.
By agreeing to pay for the inspection if it passes the seller should have no problem doing the inspection especially if you agree to purchase the bike should it pass.
I went through this and glad i did as the bike failed and had a cracked frame.
The additional cost is worth it.