Alien memetic takeover?

Here, is Alexei Turchin on the paranoid think tank LessWrong speculates on the A-for-Andromeda scenario of hostile takeover by alien memes.

If intelligent life is sufficiently rare, such messages may well just peter out ineffectively.

However, if not - and instructions for building an interstellar civilization are being sent out by aliens - it seems tremendously unlikely that they will only be tagrgetting only immature civilizations. A message that can improve most civilizations would have many more potential victims and much better spreading power. An alien virus would face an competent immune system. However, an offer of meme-sex would not face such a reaction. So: we should probably be thinking of alien pollen - rather than an alien virus.

The author of the article concludes that:

SETI serch is or useless or dangerous, and should be stopped.

However, that seems like a paranoid conclusion. If aliens are broadcasting their memes, we should absolutely make use of memetic hitchhiking, to add their technological distinctiveness to our own.