Not the same bike and not entirely the same situation, but late last summer I bought a 900SSie from a dealer that had been sitting at the dealer room for more than 7 years. It had under 6000 miles on the clock and was like new. All original tires, chain, sprockets etc. still on. It had been stored inside the shop in normal but stable room temp. It had its 6000 mile service back seven years ago before put away.
The dealer would not budge on price and did not want to change belts or anything. He was a previous authorised Ducati dealer and believed that the max 2 year belt change was overrated and because the belts had been changed at the 6000 mile service and hence was new, and because they had turned the motor once in a while, in his opinion the belts were fine.
Well, if I wanted the bike I just had to take it or leave it. This was a 2002 900SSie Senna, which is a special model year with some goodie parts on it, and not many of those existed in such a mint condition, so I just had to fork out the money.
I did get 6 months 100% warranty so I assumed the dealer was not going to sell me something that was not well kept and stored, otherwise it would be expensive for the dealer.
OK, So I bought the bike (took it for a long test ride and checked the bike for leaks before and after, all was good and the bike ran perfect) and then rode it for about 1600 miles before putting it away for the winter. I bought in the late summer, and riding season is short here in Denmark.
But when I got the bike home, I immediately changed the belts and oil and oil filter. Then I just simply took it for some long rides and I let it warm up before and was very gentle with it. Wanted everything to settle in nice and easy. Always checking for leaks in case seals etc. had gone bad.
But it ran fine with no leaks or any other mishaps. Before putting it away for the winter I took it for a good long ride, changed the oil and filter and parked it on stands inside. Now the new season is nearing and during the winter I have changed tires, all fluids, fork oil, chain and sprockets (wanted different gearing), spark plugs and only needs a valve check to complete things.
I hope it will start and stay good. My main concern is oil leaks due to seals that have gone bad due to a long dormant period.
Also to see what a long 7 years dormant period followed by a short period of running then winter dormant for 6 months and then start again will affect the bike.
I guess with bikes that have been sitting for a long time, whether new or low miles, there is always an element of uncertainty. What has not stood the tide of time well? Unfortunately seals and rubber parts are the most proned to go first if not stored in adequate and stable temps. And maybe even then.
Even though it adds to the cost of the bike, I guess there is no other way than changing all the things suggested and then ride it gently the first miles and see if anything developes so it can be detected and remedied quickly.
OK, long story short, I would change all filters and fluids, tires and spark plugs. And then just deal with issues as/ if they occur.
Guess there is nothing more to do, if the dealer does not want to do some of it or provide some warranty on the bike.
If it is your dream bike and they are rare in such new condition, you really only need to look at your financial and mechanical capacities to assess whether you are able to do those things and deal with possible issues later on.