It's funny if you look at the assumptions behind this though.
The proposal is that there are extraterrestrial intelligences, capable of crossing interstellar space (which means either physics we know nothing of or taking centuries, millenia or more), and who on arriving at the Earth spend the time needed to understand the biochemical basis of a biosphere that is completely alien to them in sufficient detail that they can engineer the organisms they find there. And what justifies this immense effort, beyond anything we could dream of doing even if we devoted the entire resources of our planet to achieving this? Apparently the collection of a quantity of a metal with no noteworthy properties except a resistance to oxidation and good electrical conductivity.
It's the mismatch between the capabilities required and the extremely mundane objective, and the idea that entities with these capabilities would for some reason regard gold in the same way that a stereotypical miser or bank robber does, that has me shaking my head. Not to mention the fact that any race so capable could doubtless obtain all of the gold it wanted far more simply.
I showed this proposal to my friend William of Occam. That slight vibration you can feel is him spinning in his grave a little faster...