Obviously there are two risks that come to mind, it might not be found to be to your satisfaction, or it might not be ready for a 1000 mile ride. But I suppose you can only lose the cost of a return trip home. Maybe a local member could be a second opinion for you, in advance? Maybe the seller is a member?
If personal safety is the concern, be sure others know where/who you are visiting and even drop a call to the local PD informing them of your plans when you arrive. Pretty remote chance of harm I would think, depending on the neighborhood? Not much different than driving 50 miles alone to an unknown neighborhood.
Suggest to drive to the pickup site.
Have cash in hand.
Inspect the bike.
Test ride. BE SAFE. Bike may not be road ready.
Make sure the TITLE is clear and in the seller's hands. No liens or co-signers or loans ......etc.
Receive signed title and a bill of sale.
Remove the license plate.
Load bike onto trailer or pickup bed.
Is the seller on this forum? Talk to the seller on the phone and ask a lot of questions. This will help to get to know the seller. There are no guarantees but the better you get to know someone the better you can decide if you trust and believe the seller. I have heard horror stories but have also heard of great adventures doing the fly and ride. If the amount of money spent doesn’t affect paying other bills it might be worth the gamble. If this is a large sum of money for you, I would advise against doing a fly and ride.
See if someone from the forum is in the area and could check the bike and owner out on your behalf.
You worry about 1000 miles - I purchased a bike in Minnesota - with much help from a guy on the forum - and then shipped it to New Zealand with no problems at all. Dont be put off by distance. Most people in the world are still genuine , honest folk.
All good intentions by the previous owner aside, any bike that is as old as these may not have had all of the maintenance necessary to keep it safe & reliable so I wouldn't even consider riding one home from that far away without first spending at least a couple of days in a reasonably well equipped shop with the Factory Shop Manual for that model (available through the CX Wiki - link in my signature) going through all of the service procedures, regardless of whether the bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on the tires and if they are over 5 years don't even think about going very far on them old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If it still has the original rubber brake lines (should have been replaced every 2 or 3 fluid changes = 5 or 6 years) you might get it home with them but I'd recommend shopping for modern stainless braided ones ASAP (they last practically forever and double the life of the fluid).
And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).