If the warranty was something offered by the manufacturer I'd contact them directly instead of dealing with the new dealer. On the other hand, if the warranty was something offered only by the now-defunct dealer I'd say the new owners are at least making a decent gesture, because the contract
(which is, after all, now expired) had nothing to do with them at all and they really have no obligation whatsoever. With the cost of parts
labor these days I really can't blame them for not being willing to pick up the whole tab.
I mean, if you had bought a new car from a Chevy dealer and also purchased, say, a paint
protection warranty which he offered as an add-on, if that dealer went out of business would you really expect to be able to just trot into a different Chevy dealership a couple of months after the warranty period had expired and get your car repainted? I don't think so!