Corrosion-resistent is not the same as non-corrosive.

I suppose gold as a noble metal would be stable over a long period, as it's non-reactive. But certain kinds of acids can still dissolve it, unlike ceramic

I can already see them rusting down by the harbour. Meanwhile people still find bits of ceramics left from ages last on the beaches.

So if you bury your clay tablets in a treasure chest it should be good.

Was his name Ea? His name isn't known today for being engraved in copper...