I am not saying it is a fake specimen, neither it is a genuine one. A simple sticker "honest seller" does not make it a genuine specimen. This is not enough for me, I need more. Pitty not everyone does and as a result we have to deal with a market poluted with fakes, that at some point will get into museums as well.
This is my approach based on my unpleasant experience from past. I have seen many fakes specimens. Most of them were bad, clearly obvious, the sellers were not even trying like they were counting on the ignorance of buyers and their only desire to cross a taxon from their desiderata lists.
Ah, I see - I hadn't noticed the nature of the current pin! I agree it's unlikely that someone would replace the old pin in an old specimen with a "new" old pin. I have in fact seen some very soft, bent old pins in specimens... especially brass ones. I have a Meek specimen with a modern pin in it, but the cut-off bit of an old pin can still be seen in the thorax beside the new pin. Someone must have thought the original was a problem, but couldn't remove it completely...
If I have an old specimen with a brittle, darkened old label, I add a new label on acid-free paper, but always keep the old one too. But I would never spend a lot of dough on a historic specimen withot having some sort of provenance evidence. I never buy at auction - always in person or though a seller I know personally.