It's not like it going to be bought quickly, most business sales take a long time. You should be fine.If someone buys it as a going concern I would think the warranty will still be OK, in any case putting a business up for sale doesn't mean it will be sold!Bought a mini city 1989 from these guys a month ago, looks like that warranty might be worthless.
Nice chaps, decided to go with them for peace of mind as this is the first classic mini I have purchased!
FS