As to dire results mentioned, I have shifted many times to big big combination and had no worst result than having to get off the bike to free the chain. I have reused pin in chain many times without failure. Not all chain brands warn against replacing pin.Apparently your chain was long enough to make the big-big shift because if it wasn't, getting off the bike to free the chain would not have done any good.
Reusing a chain pin in older 5/6-speed chains was done safely all the time. Reusing a pin in an 8-speed or narrower chain is a gamble. You may get away with it and you may not but the chain has certainly been compromised. I don't know of any maker of 8, 9 10 or 11-speed chains that does not warn against reusing a standard pin. They all provide specific joining pins or a master link.