I might be wrong but as far as I know - if the manufacturer (as opposed to an airworthiness authority) comes out with an AD or, indeed, quotes a life for an airframe it must be adhered to by the regulators.
The rules may well be different in the experimental category but it would be foolish to just assume that the aircraft 'looks strong, therefore it is'.
Seats are classed as aircraft structure so you might end up with a major mod on your hands to sling them away. Also, since they are the things that will save your life and/or your ability to walk again after an accident why replace them with inferior models?
Like many British Aircraft the Bulldog is overbuilt in some respects almost causing its own problems. It's so stiff that things crack rather than flex and wear. A sideload on the Undercarriage, for example, can crack the rear spar onto which it is mounted.